Male Fairies are so extraordinarily rare that they might as well not exist. Fairies don't normally reproduce in the same way humans do, they just sort of occur naturally and don't go away unless killed or asked very, very sternly.

I can see the main reason Fairies don't wear clothes being, well, have you ever tried to slip tiny pants onto a Fairy in flight? It is not an easy task, so one would have to somehow convince them that wearing pants is fun, or provides them with some sort of mysterious benefit. Chances are, they're just going to protect their bodies with magic if it's cold, or too sunny, and not give a crap because they're Fairies.