Maybe it's a combination of various things I've read and seen lately, but I've realized some other things that
bother me about certain animanga series aside from the "suddenly pulling ever more ginormous superpowers out of their asses" thing.
Reading the most recent volume of D.Gray-man out from Tokyopop, volume 12, had the latest version of a character or two having to batter and just about rip him/herself apart to reach the full potential of his/her abilities. What the hell is up with that? I know that you can often learn your strengths best in moments of adversity that force you to go beyond yourself but deliberately destroying your body in the hope of getting some greater power out of the process strikes me as deeply stupid. This trope is all over Bleach and s.CRY.ed as well, although at least s.CRY.ed shows some of the consequences, as well as D.Gray-Man's Lenalee (though a lot of the rest of D.Gray-man's characters doing it Get Better). Most of the time, the characters take lethal and crippling injuries but quickly bounce back. For reasons you can guess, that deeply offends me and cuts off some of my identification with the characters.
The other thing is the worship of greater strength and greater power. "I'll get stronger!" is a quote you can find in properties all across the field. More strength and power--brute force--are certainly helpful, but where's the talk of learning greater skill and finesse? Ichigo in Bleach is ultra-powerful in a way that actually prevents him from using it in any way other than recklessly and profligately. (Doubt me? The manga says it outright.) Everyone is amazed and awed by his ultra power! Then again, Bleach is also all about whose peen weapon/spiritual pressure is bigger. s.CRY.ed's Kazuma is also so powerful and effective for using his ability recklessly and overdoing it, and Ryuhou doesn't start to tap his full potential until he uses his the same way.
With that in mind, is it any wonder that most of my favorite characters are the side folks who aren't hugely powerful but are smart, highly competent, sneaky, and efficient? Add snark, and it's usually a love match. When they give their absolute all, risking their lives and health, it's during the important circumstances.