As Memnoch put it.. I don't mind the female-to-female love thing, as it's a part of the world anyway and heck, who am I to tell as to whom love and whom not
I personally don't mind that.
But one of the reason why I personally wont try this out is also the said fact: Imoen, to me anyway, in BG games is like the sister. Doesn't matter that we had different mothers, or the father was a god. God or no god, he's a father to both of us, Imoen's a sister to me, just as Sarevok was a brother and all these other... "relatives" (pertty messy family, like Adams family heh). And well, I don't romance my sister.
Of course, this may not be the issue to those who never played BG1, so the 'backstory' doesn't exist to them perhaps and they don't mind. I though played through BG1 and there's the reason.