It looks like male qunari have much bigger horns, which take up a much bigger part of their scalp. In that situation, the hairstyle becomes less prominent. The female qunari's horns take up a relatively small part of the scalp, so the hair is much more important. Could this situation be an oversight based on design choices being made primarily for male avatars, then translated to female avatars after the fact?
Well, the lack of hair isn't as big of a deal for male Qunaris in general, regardless of the size of their horns.
I want to play a male Qunari and don't think the hairstyles look good. As a solution, I'll simply make my Inquisitor bald, which will still look pretty good. In fact, I actually care more about the selection of horns than I do about hairstyles for my male Qunari. If I wanted to create a female Qunari, the option of going bald wouldn't be appealing at all and I'd care more about hairstyles than about horns.