Just for what it's worth, there were miles of differences between who I was at 16 and who I was at 22. Stating that someone is the same person at each age doesn't fit me or the friends I grew up with. I knew everything at 16, I was cocky, arrogant, had no clue who I was or wanted to be, and had very naive and superficial views of women and relationships in general.
I didn't get cooler or more mysterious as I got older. What I did do was grow up, mature, and generally get my act together. Looking back, I wouldn't date me at 16.
The thing is, when you're sixteen you don't have the experiences in relationships that you hopefully should have at 22. Everything is still kinda new and you're still feeling your way in romantic as well as platonic relationships. A lot of times you overcompensate for your lack of experience by puffing yourself up or trying to fit into a certain group. Maybe you try and be the bad boy, maybe you try to be the more sophisticated type who is above all that high school stuff by embracing different philosophies because it's different and sets you apart. But it's generally all faked at that age. You try to appear confident and secure in who you are because that's what you want to be, but how much experience does someone have who's sixteen, lives at home, has their parents pay the bills, and never has to worry much about handling the real world? You might work at that age, but it's not like the vast majority have to worry about house payments, light bills, phone bills, food bills, etc.
When you're 22, you have more things to draw on that turn that confidence and self assurance into the real deal. You don't have to fake it because you've been there, done that, if not totally at least in part. You even see it in college. Between the freshmen and sophmores alone I've noticed regularly a vast difference in priorities and social skills. Most freshmen still want to hold on to that high school mentality because it's familiar, but generally after a year they grow up quite a bit. There is a difference, and an extremely noticable one, between a guy who acts confident and one who truly is confident.
I think that's the main attraction for an older guy over a younger guy. Just the way they handle themselves makes them more attractive because you feel more like they are what they appear to be. Granted, that's not always the case, but for the most part I think people grow into themselves more by that age.