I confess that I agree, OP, but I'm not sure either of us is being reasonable.
I think Sarah Waters is just about the finest contemporary writer we have - she is superb. I really warm to her as a person when I see her interviewed, or when she writes articles.
But I have to skip over the lesbian sex scenes in her novels because I find them hugely embarrassing. I feel very bad about this because I know that, for gay people, literature is almost entirely heterosexual and they must feel very un-catered for. Sarah has implied that she wants to redress this balance a bit, and fair play to her.
But you can't help your instinctive, sexual feelings and I don't like reading about lesbian sex. That's not a judgement on lesbians - it's a fault in me, but it makes me sympathise with gay people who have not been respresented in fiction very much until quite recently.
If you don't know Sarah Waters's books, you are in for a treat, despite my prudish embarrassment about some very small sections!
Actually in my defence I would say that I don't particularly relish reading sex scenes at all - heterosexual or otherwise.