I agree, it does provide a contrast, a way to "measure" if you like the pleasure against.

Having been a former Mistress and now a very happy sub, I have seen it from both sides. To cause pain to a sub is an incredibly powerful thing, and cannot be separated from the emotional side of things. It is by definition an extremely trusting thing to be allowed to do. As I give my permission vocally for my sub to do things for me, and trust he will do them as I want, so he gives me silent permission (by not saying stop) to hurt him, to let him focus - and that amount of trust is exceptionally special.

I don't think pain should drown out emotion, it can help to focus it and at times understand it.

My master always makes me ask for the pain, to tell me what it is he is going to do for me and let me absorb the thought which is often more intoxicating than the action, and then asks me to ask / beg for it. Submission shouldn't be forced, it should be earned.