I'm a better lay than I was a year ago. I've gotten practice, I've learned a few new tricks, I've gotten more comfortable with myself, and I've gained a little bit of emotional maturity that makes me less likely to do obnoxiously needy or inconsiderate things in bed. And I'm a much, much better lay than I was five years ago. When I turned eighteen, I only had two years of sexual experience under my belt, and that sporadic and with clueless boys; I couldn't give a blowjob to save my life and I tended to go into "augh I shouldn't be here doing this" spazz attacks after sex.
As for physical aging, twenty-three's been pretty kind to me. I'm not exactly haggard; if anything I'm in slightly better shape because physical labor has put some muscle tone on me. I've also learned to dress and present myself less awkwardly. About the only "oldness" on me is simple adulthood; you can tell I'm not a kid, but I'm waayyyy too young for any negative aging.
So why is eighteen often seen as the stereotypically "sexy" age? (Because seventeen is illegal, duh.) Is the freshness of a kid sexier than anything they can actually do in bed? Innocent, in this context, is just another word for inexperienced. And not just wide-eyed "gee no one made me feel like this before mister" inexperience--more often it's fumbling, tooth-scraping, unlubricated, orgasmless inexperience. Good luck with the relationship, too; everyone has a few totally dysfunctional obssessive/avoidant immature relationships in them, and most of us get them out when we're about eighteen.
Eighteen-year-olds were great when I was eighteen, but I've moved on, and I'd rather fuck men. And that's at twenty-three; by the time I'm in my thirties or forties I can't imagine wanting more of those jabby fingers and confused "does this mean we're in love or does it mean she's a slut?" emotions. Plus I'd kinda feel like a creep.
Then again, I suppose being a creep is the only appeal for adults lusting after eighteen-year-olds in the first place. But if they actually want one, either they've never fucked a real eighteen-year-old, or they'be never fucked a really good thirty-five-year-old.