For instance, the description of the cleric's and sorcerer's class ability to cast spells have a great deal of information, but say nothing at all about metamagic, as does the wizard's class description.
This is a very poorly worded
four terms fallacy. You're comparing a "class ability" to a "class description". If you want to compare a "class ability" (more properly a class feature) to something, let's compare it to the same thing.
Specifically, consider the "Spells" class feature. The Wizard's "Spells" ability gives him a certain number of spell slots, a certain number of spells known, and a means of storing spells known in spell slots so he can expend them later to accomplish whatever the spell in question accomplishes (and places certain restrictions on when this can be done, under what circumstances, and what spells among those avialable can be learned and prepared). There is no mention of metamagic. (There is a mention of spellbooks. If we look at the "Spellbook" class feature, it clarifies how many spells a Wizard knows and where he gets them, but still fails to mention metamagic.)
Now let's look at the Cleric's "Spells" class feature. It's very simiilar to the Wizard entry, except for a few details, and that rather than a spellbook, it references "Chaotic, Good, Evil, and Lawful Spells" and "Deity, Domains, and Domain Spells". None of these class features mention metamagic either.
Finally, let's look at the Sorcerer's "Spells" class feature. It's pretty similar to the last two. The biggest difference is that rather than storing known spells inside spell slots at ahead of time, he does so when he casts it. Thankfully, it don't reference another class feature-- all the rules for what spells a sorcerer can learn, know, and cast are right there in the "Spells" class feature with no further clarification.
Now, returning to the wizard, let's look at the "Bonus Feats" class feature. It's very similar to the Fighter's "Feats" class feature, in that both grant the respective characters additional feats above and beyond those that accrue with hit dice. The main differences are how many additional feats are gained, when they are gained, and the list of feats that may be acquired in this manner. However, every character gets feats. The Fighter and Wizard simply get more of them. The way feats work is that, once you have it, it either improves one of your traits or lets you do something that you couldn't do before. Normally,
nobody can use metamagic, but if Jim the Wizard (or Mike the Sorcerer or Steve the Cleric) takes a metamagic feat, he
can. Similarly, under normal conditions, nobody can subtract from their weapon attack rolls to increase their weapon damage rolls, but if Kevin the Fighter (or Alex the Barbarian or even Jim the Wizard) takes Power Attack, they can.
And actually, Kevin the Fighter could take metamagic feats if he wanted-- the core ones have no prerequisites. He just has no "Spells" class feature that would permit him to benefit from the feat. Even if he knows, hypothetically, how to modify a spell to operate differently, he doesn't know any spells to modify or have any spell slots from which to cast them.
Of course, what I find interesting is that the text as written appears to limit the restriction to druids of first level. It would have been easy and not awkward to describe the class ability in ways that unambiguously limit the companion to being normal at all levels. For instance, "Animal companions are completely typical for their kind excepts as noted below." or "Beginning at first level a druid may summon an animal companion that is completely typical of its kind except as noted below." . . . etc. etc. But it doesn't say these things. In fact, the reference to "1st-level" is completely unnecessary as you've interpreted it, because the prior paragraph identifies that the druid begins play with a companion from the list of animals there--so we've already been told that a druid may gain a companion from the get go. One could tenably--and I would argue reasonably--conclude that the inclusion of the "1st-level" modifier here is purposively there to do what what I'm suggesting, limiting the typicality of the companions to first level druids. Why this is a rule, I can't tell you. But, to me, it appears the stronger of the interpretations, RAW.
My guess would be that the text went through multiple revisions and the editors felt that the intent was clear enough, or didn't anticipate your interpretation. Yes, a lot of class features start with "Beginning at X level..." or, for those available at first level, "A Y can..."
But the Druid isn't alone in this awkward wording. Consider the Barbarian's "Rage" class feature (the last paragraph, beginning at the second sentence):
"
At 1st level he can use his rage ability once per day.
At 4th level and every four levels thereafter, he can use it one additional time per day (to a maximum of six times per day
at 20th level)." (
bold mine)
Given your reading, we have
no idea how often or even whether a Barbarian can rage at 2nd, 3rd, 5th, 6th, 7th, 9th, 10th, 11th, 13th, 14th, 15th, 17th, 18th, or 19th level. We just lack that information. Perhaps they should have started with "
Beginning at 1st level..." or simply "He can..." Do you really think the writers intended the Barbarian to go without this iconic class feature for nearly 3/4 of his career? Or did they intend for him to have unlimited access to the ability at those levels? Or, like most class features, is he intended to gain access to it as described and continue to make use of it in that manner until further descriptions modify it?
Do you really want to steal from the Barbarians to give to the Druids?
Moreover, based on your proposition/interpretation ("When you gain 'a new one', nothing says it's any different from your first one, so it's not"), a druid would not be able, at least until fourth level, to gain an eagle when she first chose a riding dog because nothing in the rules says you can select anything "different from your first one." While I suppose there are good flavor/story reasons to interpret the rules this way, I don't think that's what the rules say.
That's clearly not what the rules say, and I'd like to thank you for providing an excellent example of one of my points above. I didn't read what I'd written and think about it carefully enough, and I didn't anticipate the manner in which you interpreted it. When I said it's "not any different", perhaps I should have said "it follows the same rules outlined for acquiring the original". Being forced to recruit an animal of the same kind as an earlier companion is in contradiction of the rules, since you are explicitly permitted to attract an animal companion "
selected from the following list" (
bold mine). What I also meant when I said it's "not any different" is that no new procedure is listed for generating companions that weren't available at 1st level (except the expanded list of kinds of animals available to higher-level druids). Until new options are added, only the original options are available.
While we're on the subject, if a 2nd level Druid's companion (and, by extension, a 4th level Ranger's)
isn't "typical for its kind" (aside from those traits gained from the chart), in what ways is it "atypical"? Does it generate ability scores like a PC? Is it strange colors? Does it breathe fire? Is it a creature type other than Animal? Does it have an unusual selection of feats? Just like the level 2 Barbarian, we have no idea.
While I agree with your interpretation here, I am not sure how this sits comfortably with your "nothing says it's any different from your first one, so it's not" proposition. Be that as it may, we agree that it is possible for a druid to apply an acquired template a companion under the rules.
The way it sits comfortably is that the "Animal Companion" class feature only describes the traits of an animal with with the Druid "may begin play" or "may gain a new one". Once play has begun or a new companion has been gained, other events may modify the companion's traits. The class feature only describes the companion when it enters play.
No need for you to conclude with a straw man here, as I haven't proposed that the absence of a prohibition makes the rule argument. What I have said is that given the RAW language about "1st-level" druids being limited to typical companions, I have not seen a rule that augments, expands, or interprets this at all.
My apologies if I offended you. I wasn't trying to construct a straw man argument in my earlier post. (I'm still not trying to offend you. If I seem excessively specific, it's because I'm trying to develop a clear, logically sound argument without excessively broad interpretations or ambiguous phrasing.) However, it kind of sounded like that's exactly what you were doing. Maybe experienced Druids aren't restricted to "typical" animals, but without knowing what makes their potential companions atypical, we don't know definitively how to generate properly atypical animals for use as companions. From what I can tell, this leaves us either continuing to generate typical animals, which we know how to do, or the madness of every option ever (perhaps 36-point-buy advanced pseudonatural half-dragon magebred war badgers-- and no, I didn't actually check to see if such a creature can legally exist). I don't necessarily think that's where you, specifically, were going with this, but there are a lot of weird people around.
Okay, I suppose there's also the option of resigning ourselves to being unable to generate companions for experienced Druids, but at the rate I've seen Druids go through companions, that would make for a lot of lonely Druids very early in their careers.