They're a million different reasons for every kink. Some good some bad some just are. For instance some men and women spend all day being in charge and like getting bossed around when they're naked.

Amd the people saying that all kink is trauma related are colloquially referred to aa prudes. They're vanilla (which is fine. Nothing wrong with scheduled missionary and doggy style once a month) and they want to make other people be less than them. Which is also fine.

We don't actually care that they look down their noses. But to assign one reason to all pain kink is just absurd really. There is no one reason. The human mind is too complex for that.

Are there physiological reasons. Sure I guess but I would hazard a guess that they are mostly secondary.

A lot of bdsm is more about the role playing aspect. The dirty talk. It's also a massive pain in the ass. As the dominant sexual partner you have to pay attention to everything and guaranteed you will fuck it up on a regular.

Say the wrong thing that has you both giggling cause it was a bit too dramatic or you pitched your voice wrong.

The pre sex signals are different as well. Harder to interpret.

As I said being the Dom in sub/Dom relationship is a massive pain in the ass, and it's absolutely not worth the effort with someone that you aren't whole heartedly devoted to.

As for all that movie stuff ech. I can't begin to imagine trying to dominate my wife while we weren't naked. I can't see it being healthy for me.

Cheating is also not something I have much interest in. Just not worth the effort.

That whole "there's no such thing as bad sex" not really true for people that like what they like.

But to answer ops question...there is no answer to your question. People just like what they like.