The difference between "game that includes sex" and "porn" is essentially the same as between "game that includes shooting" and "target range". And if masturbating is the main activity - there is no need for game. You can just go to (massively NSFW) e621.net, for example. The main activity of game is playing, not something else. It is not about "sexy stuff suffering in service of the RPG stuff". It is about sexy stuff suffering from being nonsensical and being an end in itself. Some may find "revealing" armour sexy. I find it disgustingly stupid. And for me "stupid stuff" is dominantly antagonistic to "sexy stuff" (as in "something that is stupid cannot be sexy; no exceptions"). And there even is no good in-world reason for existence of such things. Revealing garments belong to brothel, not to street, dungeon, wilderness or battlefield. But in brothel - sure, whatever floats your boat.