I believe the correct answer here is "because boobs."
Me and a buddy were talking about this the other day. We are both on there probably once a day but both of us said we rarely check out the chick pictures anymore. It has gotten redundant. Yeah, Wednesday, another 30 girls with great *****. Yeah, more gorgeous women. That part really isn't a big deal anymore. I'm more interested in the humorous stuff than that but, hey, if I want to check out women it works for that as well.