I'd argue that one of the reasons as to why breasts are considered to be more appealing is due to their prominence in the media. In earlier civilisations - such as The Roman Empire - it wasn't unusual to walk around and see nude statues of both women and men, nor did many bat an eyelid at the idea of appreciating the aesthetics of both genders. Now, obviously we don't need full on nudity within FFXIV but the shift in attitudes towards anatomy is very much a consequence of 'modern' society.

I'm also not convinced that it is truly a 'minority' of people who appreciate such aspects of the male form, either. Up until recently, people were persecuted for their sexuality after all - and in some countries, they still risk being killed for it. I imagine that plays a large part in people being quiet about their tastes - and it's very telling that when progress is made in regards to the acceptance of sexuality in a particular country then there's a lot of people who come out as homosexual or bisexual.

On a related note, from an in-game lore perspective sexuality is something that doesn't really bother anybody within Eorzea. It'd be nice if that could be reflected by the character models to make such a stance feel authentic. In a tasteful manner, of course.