Well, first of all the way I see it nothing should be mandatory.
I do not just enjoy anal, it makes me cum faster and harder. So as I take care of my partners and make sure they have a good time, I expect to be treated in a similar way. I think this mentality it is respectful, caring and it allows - myself at least - to enjoy sex with random men a lot more.
Saying that, I am always very upfront about what I like so people who would have an issue can pass early on. Each to their own!
Stopping the rant as I am semi horny and will go back to it.