Skippable and avoidable/optional are two very different things. While the first one skips the scene, they tend to still happen in the background, which is for some fetishes not really desireable. Avoidable or optional are prefered, because, then you (as the player) can prevent things from happening, meaning the choices do have some sort of impact.
The thing is, people would like to be able to avoid certain fetishes or LIs. With avoidable or optional content, you give them the choice to do so, with skippable you have basically a KN, where the at least the aftermath of the skipped scene could still be mentioned.
Just as a advice to keep in mind.