The issue seems to be you're viewing it through the myopic lens of only "optimized" characters. Many (most?) gamers don't play that way. If I'm hitting often why boost it more when I don't need it and I can take cool stuff for my character instead? Some times that will mean multiclassing and power swaps that may or may not be mechanically "optimized". For example, my Thaneborn Barbarian took a Warlord multiclass because the it fit the character concept I wanted. Mechanically he'd have been better off taking the Sorcerer one that would have fit his Paragon Path too but the Warlord one gave him the Diplomacy skill training he needed and a leaderly boost to his allies on action points (and initiative with his Helm of Battle, also a flavor choice to fit the character concept.) He still hits well, does his copious amounts of damage but isn't about being "optimized" for solely combat.
I, too, fall into this methodology. If I feel my character is "hitting enough" /defense/skill/etc then I feel perfectly fine not investing the feats to increase accuracy/defense/etc. And anything I do miss, I don't really give it second thought because I am content with whatever I chose instead of the increased accuracy. Conversely, if I were playing a combat-oriented tactical encounter game with no real story to speak of, sure, then the value of some other feat options would be lessened for me and accuracy would be more important to what i want to do for that game scenario.
It's a matter of cost-benefit and preference. Is the cost of the feat and opportunity cost of that other feat not taking worth the benefit of increased accuracy? Some will say yes some will say no depending on the circumstance and what the modifier currently is without it.
Having said that, in the groups I've played with, I see some players who place a high value on accuracy (or defense, or some skill, etc) and therefore take every feat choice to maximize that -- it is their prerogative and nothing wrong with that either (they chose to give up some other option for the accuracy).
It does seem odd, however, when you have both of those types at the same table. You'll have one PC who only needs a 2 or higher to hit while another needs a 12 (that's an extreme example, but i've seen it happen more extreme than that than that). same could be said for defenses or a specific skill check like stealth, etc.
so, really, i think it comes down to preferences and cost-benefit choices. Yes, there may be a 'target' ideal somewhere in there that the designers imagined. But if it works -for you- then it works (period).