Well, since it came up in the conversation... not sure how it's relevant, but I find B2B a turn-on, and G2G a turn off.... as well as G2B, for the most part. I usually don't enjoy any porn that features females, which I always thought made sense since I'm not interested in females... but I seem to be the minority here.
It's less of an issue in written porn, though, as long as it doesn't spend time describing the female (I skip these parts anyways).
I usually prefer B alone, though. B2B a close second.
I personally don't see why it would be wrong that people be accepting of other people's tastes. I certainly wouldn't stop two women from having sex or a relationship, and the fact that I wouldn't enjoy watching it just means that I don't watch it. As far as I know, most of them wouldn't want me watching them either anyways.