I have this problem. Not to brag but a lot of people tell me I'm beautiful but I don't have a man and haven't had one in a long time. Part of my problem is actually me...I'm too shy to even let a guy know I like him! People say I'm intimidating but I don't really know why I would be other then the fact I'm quiet. :/
Another thing is hot girls make a guy think of sex. Not saying that all hot girls are easy, but they give off a sexual vibe which attracts guys. Beautiful girls are still attractive but don't present a sexy vibe. If there are 2 pretty girls and one of them looks like she's a good time and the other one is reserved and conservative...obviously the guy is gonna go after the one he has a better chance of having sex with.
Well maybe the beautiful girls are too intimidating to guys. In highschool the most beautiful girl was always single. I would always tell my friends maaan I wish she was my girlfriend. haha. I never approached her unfortunately, I'm not a bad looking guy either its just I was too shy.
Girls' idea of "beautiful" is completely different from guys' idea. For instance, girls often think that Julia Roberts and Audrey Hepburn are beautiful, but guys are rather meh about them. So it could be that there's just a misconception here.
In my experience, the "hot" girls were more open and obviously flirty, but the "beautiful" girls were the ones who knew the value of a good chase or not putting themselves out there for everybody. I've never been called hot, but have been called beautiful by all but one guy I've had a substantial (more than 3 months) relationship with. Hot girls aren't sluts, they just know/feel guys should want them, and promote it.