I like it when there's a large, WELL-WRITTEN variety of romances. Of any sexual orientation. I find that romances can add to the game, but not if they only serve as a dating-sim style 'tick right flags, have a sex scene.' Done right it can serve to add an interesting extra dynamic to a character, but done wrong it can drag everything down.
Oh, but I don't want it to possible to romance everyone as anyone. There's something uncanny, and immersion breaking about everybody in the entire universe being bisexual. That and it screams 'these character's are just here to spread their legs for you,' which I detest.
That said, I don't see why they wouldn't have them in the game at all. If you like them, you take them, if you don't, well, it's possible not to take them, surely? It doesn't feel like implementing the option would drastically affect the experience of those who don't wish to follow a romance plot, or am I missing something here?
Side note: OP, in your poll what do you mean by 'well behaved'? This phrase carries odd connotations...