Why do girls wear tight pants?

[Tutulover!]

I don't wear pants, I only ever wear dresses and skirts but it's because it looks better, baggy pants is a big NO NO!

[Charlea]

They are much more flattering. They are slimming and even people who don't like their legs know they will look better in tight pants than in something baggier. They are feminine and simple, they go with every style and they're fairly practical.
It's hard to explain really why something is in style.