I don't want to get totally sidetracked by anthropology (even though it was my undergraduate minor), so let me say that I share your sadness at the effacement of cultural difference. I would suggest that different forms of life emerge from & create distinct environmental & social conditions & just as we should preserve biodiversity, both for our own selfish ends (medicines, air) & in a more general ethical sense, we ought to preserve forms of life--never know when one might come in handy, after all. The market is an ass.

Pain: Okay, I understand this. There is a fundamental bodily identification; but, my bluetick hound is old & sick right now & while I don't come to her exactly as I would come to a suffering human, she says in her way, "This hurts" & I respond by saying, "Yes, sweetie, I know it does." So if we are going to understand the dynamics of forms of life to this fundamental level, we will have to include animals. I suppose that with dogs & cats & a few other species, we already do partake in the forms of life of animals. Still, giving the body its due, I remain an epistemological skeptic when it comes to "getting inside" another culture. Marriage may (potentially, in some cases) be an exception--some of my Vietnamese friends urged me quite seriously to "get a Vietnamese girlfriend" in order to learn the language. My Vietnamese teacher, a rather proper middle-class woman of fifty & the mother of two grown sons, surprised me one day by saying, "The best place to learn a language is in bed." Those Vietnamese, very pithy! I refrained from asking her if that was where she had learned Russian. At the same time, when you write, "Other cultures allow us to at least entertain alternatives that would be unimaginable if we were to think of cultural boundaries as impermeable," I understand this to be ethically true if not practically true. (Maybe when we're done with Wittgenstein in a couple of decades we can move on to the American Prgamatists--if we are able to move at all by then.)