I half share your opinion.

Half, because I like smut and erotica from bodice rippers to porn with plot, they are fun reads for me. Even the bad ones when I'm in the mood for "trashreading"

But I do agree. And I think it doesn't just seem unnecessary, it is unnecessary very often because of various forms of bad writing. And it's a literary turnoff for me, too, despite being into a variety of smut.

Very often the story would benefit from a fade to black with aftermath, or poetic two paragraph descriptions of intent and emotional state, because the scene doesn't contribute to the story. And even when it could be a good addition to enrich or move parts of the plot, it's often just something detached thrown in, and I feel like it's only there to get a 🌶️ rating from reviewers. Plus these authors seem to not have good experiences to draw from and it leaves the scenes empty and confusing.

And repetitive. Big problem, too. If it's repetitive it doesn't need to be there no matter the scene. Some people can write 40 smut scenes in a 30 chapter work and make it matter and different, but it's way more often the exact same emotionless scene almost copy-pasted again and again.