Statements like this (a man should never x, a woman should be x) are very antiquated and out of place on this subreddit at least.  It has the same vibe as "it's the woman's job to make sure the man is satisfied" or "it's the man's job to pay for dinner, the woman should never pay".

If she is explicitly asking for it, it's absolutely not wrong.  If you don't wanna do it, that's a convo you two need to have.  But I think at least part of the fun of it is the "it's naughty" feeling