You know I think it may be the way they are dressed. Some of them are dressed very mature, some are wearing things some people don't really wear until they're in their 30's. I don't know, when you're in your 20's you're supposed to have more fun w/ your look, more color, more whimsy...some actresses aren't dressed like that. Idk if that is their personal style or they are professionally styled to look that way.
I agree w/ the comments about Kim, and as for Weir, I think dude aged appropriately. In his early lakorns, he did look very young, and now he looks more manly (that is, more muscle mass...hehehe). I think his face aged appropriately too, b/c before it was so baby faced. I like Weir now, more so than back then, just my two cents.
Yeah- my 700th post!