Maybe I'm just weird, but I get a kick out of wet butts. I think it's funny.
I get why people do it though, because pausing to break out the lube can kind of take away from a hot and heavy scene I suppose. I've seen some authors who integrated it as part of the play/fun, but there are others who want to just get to the point. Kind of a "different strokes for different folks" thing.
Also, I've seen people go on about needing a high level of stretching-- I won't go into details but if you know, you know-- and that is not actually always necessary IRL. Can be, sure. But is not always required. So it's a misconception usually perpetrated by women who haven't... uh. Had that experience.
I used to feel really annoyed by omegaverse stuff (I personally just don't get it) but after a very good ftm trans friend of mine said it made them feel kind of cool and represented in an abstract way, I've really changed my perspective. Still not my tastes, but I don't fault it anymore.