Which is kind of sad really - I mean I know Spider-Man was originally intended to be the "loner, the sad sack, but he's a hero and does what's right" but y'know that was 50 years ago...
Considering that the MU only sort of 're-jiggers' things and doesn't wipe away decades of continuity - lookin' at YOU DC - to keep their characters 'youthful' it's sort of a double edge sword. While I wouldn't want to watch a 60 year old Peter Parker, I WOULD be down to seeing a grown adult Peter doing adult things and standing side by side with Cap and Iron Man and the others and not being looked at 'who the hell let this goofy kid in with all of us adults?'
That's why I always supported NEW or legacy 'teen'/'youth' characters like the original New Warriors and the MC2 line and even to an extent X-Force since it seemed like all of them grew up a bit.
I'm honestly quite happy to see Kitty assert her womanhood lately, finally. Where she's still young maybe, but she's mature and adult enough to say stand with Storm and Psylocke as a peer and not 'remember when we bought your first real bra?' kind of age. I'm even happy to see that younger characters like Rahne Sinclair who was younger than Kitty even for most of her time in New Mutants, grow up.
But it seems like for every one character that's allowed to grow up, there's at least one that's left permanently in one point. "Forever 21" isn't just a store to them, it's their life.