Why do girls wear tight pants?

[Pestychin011]

So I've been wondering about this for a while now... But what I mean is that people everywhere are ALWAYS wearing tight jeans, and I just don't understand it. I'm not saying it's not okay to wear what you want and embrace your style or whatever. I just don't get why they are in style apparently. Every girl I see, whether it's a picture on tumblr or facebook, twitter etc, youtube videos, TV, girls at school, practically every occasion.. I just keep seeing tight jeans. I swear that's all they wear! And I don't get it or know why. I don't think it's just because mostly women are trying to show off their curves and trying to get attention.. It seems a lot more casual than that. What really bothers me is that whenever I try to wear something like that, I end up getting called fat or something and I don't see that many other people hearing this. And I'm quite small. I'm actually very insecure with my body. So I don't see how, when many other pple aren't that confident with their body, wear this. I don't have a problem with what they where. I just don't get WHY it's in style. Please don't just say,"It's comfortable." I'm pretty sure there's more to it than that. I mean baggy pants like capris are comfortable..
Thanks everyone for the answers. I'm sorry if I seemed offensive. I have to admit that I'm behind on what's the latest style or what's modern right now. It's just that my parents don't really buy me clothes so I don't have that well of an idea of what's good out there.