It's weird when TV shows and movies have really advanced alien species that, for some reason, don't wear any clothes. Is it just our strange luck that we keep running into species that just decided one day, "Hey everyone, let's be nudists!" "Hey, that sounds awesome!"
What's even weirder is an alien species in Torchwood. Called Weevils, they are no smarter than animals, and live in the sewers, yet for some reason they all wear clothes. The same uniform, too.