The trouble is, I think, that Teamwork is only ever made easy for spellcasters: It costs little focus to cast a buff spell, or a debuff. It encourages pre-battle teamplay, but in battle? A great teamplay spell, for instance, is Bigby's Slapping Hand. Arrange your fighters and sneak-attackers around the guy and then have him provoke. But who takes that? And prepares it? The trouble is that there are usually better spells on many levels, which give a direct benefit, and don't really rely on who or what is fighting with you, just someone who makes the guy dead eventually.
Non-casters basically have to rely on being buffed, and otherwise have to be content with being "the wall", or the BSF. However, even non-casters together COULD benefit a lot from teamwork, but most builds favour egocentricity. If taking team feats lowers your damage output or your self-reliance, then they hardly seem worth it.
There should be more feats that give direct combat benefits to teamwork, while not reducing individual combat power too much. And they should be more straightforward, perhaps, and not require too much in terms of combo-strategies.
Now I have to say in groups I play it's really not as bad as bearsarebrown says. However, there is USUALLY a critical lack of tactical communication ahead of any fight. Basically players don't plan much for battle in D&D, nor in most other games I've played, except perhaps SR, and then only on a larger scale. Strategic tactical combat, i.e. optimised for maximum total output, instead of maximum personal output, is not that common.
I think WotC did a good thing with Crusaders, since a crusader can give a lot to a party when played smartly, however, I sometimes feel that Crusaders in turn give up a lot of offensive focus. They have to concentrate on single-attack maneuvers, and for all dippability their healing-mechanic doesn't scale too well, and you can be randomly fucked by drawing the wrong maneuevers. Also, in order to bring their BFC effects to bear they need to put extensive efforts into extending their reach, which is not facilitated by the class itself.
Also, the direct rule effects even of tackling an opponent in pairs or groups aren't that great - I guess intentionally, because PCs in D&D should often face groups of weaker foes. In other games, facing a group often means near-certain demise, even if the opponents are weaker. This loses a lot of heroic feel, I guess, but does make teamplay immediately more attractive. For instance, if flanking benefits were to increase per teammate fighting the same enemy, then that would encourage sticking together. As it is, you need at least two feats to even get a flanking bonus when you're just fighting (and not really flanking) the same enemy, and that's
only a +2, unless you have a sneak-attacker.
And I do have to say: All my examples are still really from lower tiers. While you can make a point of playing a GOD wizard, you're still not really being a team-player, you're just pretending to be one. (You COULD, with just a reduction of pace, also do everything by yourself.) As a Wizard, you might as well spell it t11m
. Druids make decent team players - by themselves. Sorcs occasionally need support. The Tier3 casters actually do make decent team-players, because they usually lack one element of the all-encompassing tactic - DNs need logistics and Beguilers need damage output.
I think some problem lies in the fact that it's actually pretty hard to make up diverse team tactics. Stacking debuffs and then hitting them with an SOD is a good and effective tactic, except, if that's what you do every time then it can get old, too. Also, no DM around me will let you get away with it for more than a few times, they'll start optimising against your tactic, which IMHO shouldn't really happen. So you really need different ways to act as a team which do not a allow the DM to completely shut down your tactic by taking out a key step. (For instance, by using Undead. Or whatever.)
So really, the problem lies in the fact that, while D&D was originally designed as a cooperative game, where no one could shine alone, it's really the case that the designers messed up this aspect pretty well, which forces players to intentionally seek out this component.