The all-heads-attack-and-move part probably is broken, the 7-attacks-part is powerful (but probably not legal).
Not legal? I keep seeing this asserted, but I'm the only one in the thread actually quoting sources, and the quotes I have contradict this line of thinking. I'll provide another quote below.
Oh. You really think that by "broken" it means "not what the developers intended." In that case, no, it's not broken. The developers wrote out examples that show they clearly do intend for the wizard to get the full claw/claw/bite (or whatever) sequence.
Which ones? Do you have a link?
I already provided the Skip Williams quote, which you seem to dislike. So here is another: in the official WotC product, Shoals of Intrigue, the antagonist Junparrt "can shift into tiger form as though using the polymorph self spell." They then list his stats in that form, which includes... 2 claws and a bite attack. Page 11. Normally he gets 1 attack, so how'd he get all 3 attacks? Did this official module break the rules?
There is
another Skip Williams article where he addresses the discrepancy between gaining natural attacks and having a limit on "no more attacks" than usual. He suggests that it is resolved as others here have hinted: it applies to weapons. You can either use the natural attacks of the creature, or the weapons you were trained with, but if you use the weapons you were trained with, you can only do as you were trained (two arms). If you use the natural attacks, they work as they do for the creature. He writes: "You can make attacks that are "normal" for you
or normal for your assumed form, but you can't combine them."
Finally,
our own Polymorph guide cites the hydra for the extra attacks. I concede it's the least authoritative of them all, but it highlights that the belief is popular even for those who are experts with the spell.
In regards to the thrust of this discussion, Wizards of the Coast is consistently following the advice in the articles by Skip Williams. So either he interpreted it wonky and yet a company-wide edict was issued to follow him, or they had already led the way and he merely reported it accurately. Either way, they're consistent on this front. If needed, I'm pretty sure I can go through more official modules and find more instances of polymorphed creatures having full natural attacks.
If we follow the idea that we are limited by BAB for natural attacks, we go against these examples, the "Rules of the Game" articles, even the Rules Compendium (which notes that natural attacks do not follow BAB, page 100). However, if we follow these examples, suddenly
all this material is in sync and works.
So why would we argue against Wizard's own documents and mire ourselves? If it's because we think a hydra is overpowered, why not say, "Hydras are overpowered" and be done? House rule it away. Trying to argue that the spell never intended for natural attacks to work when there is so much evidence otherwise is... crazy making. Nerfing a spell by debating something with loads of contrary evidence is going to be a miserable & difficult way to nerf the spell. A house rule is clear. "The spell didn't mean to do that" is a debate. "I don't allow that in my games" is a decision.
So I'd caution us. If we're trying to advocate the spell be interpreted in a controversial way merely because we dislike the hydra, we have an uphill battle before us. We're trying to make "interpret the rules" serve the purpose of nerfing the spell even though people can interpret the
opposite way.