You didn't describe every single shy person ever (believe me, I know a lot of shy people who are still boring as hell when they get comfortable with you), but you did describe me perfectly (at least from what I've heard from my friends).
If you're a nice guy, why would you concern yourself with what the dumb-but-cute girls think of you? Or are you not interested in nice girls? Because that would be tragic hilarity on a cosmic level.
It's just a matter of which league you're in, because there is a set of leagues. They're not graded, like they usually are. They're just different leagues. Each league is, however, loosely graded by the popularity of the people in the league. Each person can be in multiple leagues, but the leagues you're in determine who you're most likely to be friends with, and you're most likely to be hit on by people from your own league(s). One of these leagues consists of nice but unpopular people, and another consists of nice popular people. Which leagues you can be in is determined by the other leagues you're in. This means that a nice, plain, and somewhat popular guy can normally not be in the same league as unfriendly, ugly, and unpopular girls, but the same guy can be in the same league as nice, plain, and unpopular girls or nice, sexy, and popular girls (just for the record, this is me).
Most girls who say they want nice guys usually aren't anywhere near that league, as almost none of the "nice" leagues also contain "undramatic" and "popular" (usually it's the polar opposite), which most girls who say they want nice guys are.
I know that I was unclear, but I didn't write it to be understood by everyone. I merely wanted to state my opinion to anyone who care enough about this to read my comment thoroughly enough to understand what the hell I say.
Girls choose jerks not because they're idiots, but because the jerks have learned how to act like a nice guy. Then once they have the girls attention, they go back to who they really are. But the girl stays because she hopes the jerk will go back to being nice. Same for guys who are with horrible girls.
This, in my experience anyway, is rarely the case.
Edit: I've often gotten the impression that the cute girls go after the douchey guys so that they won't have to bother with any self-improvement, or anything other than partying and effing around. It's like the reverse of the high-maintenance thing. They just want something easy, because much like the rest of their lives, they just want to coast.
Stop taking advantage of them as well
...wait why the quotes :(
Edit: I've often gotten the impression that the cute girls go after the douchey guys so that they won't have to bother with any self-improvement, or anything other than partying and effing around. It's like the reverse of the high-maintenance thing. They just want something easy, because much like the rest of their lives, they just want to coast.
There's also lucifer