Celebrim,
All good points.
However, IME (although that may be limited), I have not seen too much rotation between missile and melee combat. Rather, at least PCs, tend to stick with one or the other. Even if they do both, missile generally only occupies the beginning of the combat. After all, who "sheaths" their bow once they are in melee? The bow is dropped in favor of a melee weapon. Moreover, quickdraw is required to get that full attack in. If the opponent wants to revert back to missile he has to drop/sheath his sword and then pick up his bow getting at most two attacks in (w/haste).
The other option is to just fire missiles, but than you run into the problems of cover, lack of threatening an area, and AoO while firing while threatened.
What I have seen is the chase, where the character chases his opponent around. You brought up the charge, but remember that requires a straight line. This can be very limiting in the right environments, namely, anything other than open space - forest with trees, mountains with rocks, hills with trees/bushes, desert with cacti, room with table/chair/desk/bed, etc.
This in general always favors the chased with the caveat that they have a greater movement. Moreover, even if the opponent can charge, the bonus to charge is pitily in comparison to the defensive benefits from the combo I outlaid above. On the other hand that is fairly specific. But it certainly could be made more general. Even if all one did was use expertise, or fight defensively with tumble, the chased still wins out. Especially given the fact that the next round, along with the armor halving, the character now also has an additional -2 to their AC.
Too often I notice that it is the case that a character tries to achieve more actions in his turn without keeping track of his/her opponent's number of actions per turn. The advantage for gaining additional actions comes from having a higher number relative to the opponent. In this case of this feat, you give your opponent an advantage by reducing your number of actions to his. To offset this balance you need to find a way to reduce his number of actions or increase yours. In general, your opponent can increase his actions the same way you can (e.g. you both can be hasted, for your TWF, the spellcaster has quickened spells, etc.) So, unless your opponent does not have access to these benefits, it is up to you to in some way reduce them. This can simply be done by interposing distance between yourself and your opponent with some sort of obstacle or beyond your opponents charging range. The catch is that while this would normally effect you and your opponent equally - neither of you gets to do anything, you have in fact gained some benefit.
So, the point - while it is true that it may be a wash between the stats (which it certainly isn't always - that is completely dependent upon the armor bonus), it is not a wash if you reduce your opponents number of actions.