Well they can if they want to. But I think that as of these time and area. That's not consider something a respective men should wear. You know what I mean. Maybe in a few years it might be acceptable or even fashionable. but right know it seems not to be.
There's not really a good reason, actually. It's just tradition. In bigger cities it's actually not unusual for there to be a lot of guys who like going out to bars wearing dresses, and not as a joke. Most of those guys aren't gay, either. They just like how dresses look and feel. If you want to wear a dress as a guy, there's nothing wrong with that.
But some people aren't very good at being respectful to people who act different than what they're used to, so in places outside of big cities, where people aren't used to being around all different kinds of people all the time, most guys who wear dresses do it in private, because they don't want to be made fun of or treated badly.
People used to think it was weird and ugly for women to wear pants. That wasn't too long ago, either. Hopefully someday it will be okay for everybody to wear what they want and not worry about what gender is "supposed" to wear it.
Boys can wear dresses if they want to. They will be made fun of and all that stuff, but if you like dresses, then wear them and don't pay attention to what others say or tell you. Be yourself, Be original. :)