They want to be skinny to attract male teens.
If you are looking for reasonably priced colored skinny jeans check out Blank Jeans, as well as plenty of options to wear with your jeans at www.edgeofurge.com u can go there or u could just go to...
All of the teen titans except for Cyborg are rather thin due to the fact that they are all young teenagers, and not big, buff adult superheroes.
Most likely, skinny jeans anre worn in many countries around the world. So, if they do it is normal.
like 67% including some teenage guys