Some may, but others, like myself, like a well-constructed ass attached to a female. There's nothing particularly wrong with liking boys, but the geometry troubles me and I prefer women as a result. Since male breast development occurs about as frequently as female breast development beyond American C-cups by the (admittedly few) estimations I've seen, it's not like breasts are uniquely female - but far fewer males than females have the kind of development on the other side necessary to elicit the response self-proclaimed 'ass men' desire.
Jeff
Well you do have a point. Men can grow their own pair of tits but they'll never reach the awesomeness of the great female ass, and fuck am I happy to know that.
There's been a few instances in my life though, when I've spotted a nice ass, and to my horror, afterwards noticed that the owner of the said ass is in fact not a female. It might still be a great ass, but you may no longer want to admit you think it's a great ass.
That said, I've seen manboobs more often in my life than I would have liked to, but never have I mistaken them for the real thing. Therefore, I think tits win.