As long as the adoptive parents teach the kid some form of sign (or at the very least, cued speech. I don't think lipreading is very helpful since it's so tiring and a lot of guess work) so that they have some way of communicating more than 'food', 'drink', etc with them, why not? It's when the parents adopt one and seem to think they can 'fix' it and make them hearing, not allowing them to use sign, etc, that's unfair in my eyes.
Speaking of which, I saw a kid (bout 10?) a while ago. He was probably moderately deaf or something, because he had really expensive top-notch hearing aids. Problem was, he didn't want them in, and his mother hit his hand when he tried to take them out, and told him he has to keep his hearing aids in because otherwise, he "would never be normal" wtf is that teaching him? I was so irritated with it.
I would love to adopt a Deaf child myself, but right now I'm nowhere near ready for that kind commitment to adopt kids. I've got two small children of my own, maybe when they're older I'll think about it.