Why don't girls wear dresses anymore?

I'm assuming you mean little girls and not just girls in general. little girls don't wear dresses because they are not conducive to active play which modern-day children need more of than looking cute due to obesity scares imo.. Girls in general don't wear dresses because they are often uncomfortable, embarrassing to walk up open staircases in, blow up in the wind, and are less adaptable to various weather situations.