Why do so many people want NSFW games?
They don't. That's why those games are under attack. It is an easy target. Publicly defending them is something few players of such games will do. But attacking such games is a thing many "concerned citicens" will do as a lip service, making it easy for fanatics to have their way.
Itch has a sizeable amount of adult games, compared to other platforms, because they allow indie games that are unfinished and free games and till the recent trouble games with certain content that was not allowed on Patreon. It has maybe 10 times the games that are published on Nutaku. That's a very rough estimate. Nutaku has about 1k games. Itch about 10k if you do not count double entries and shovelware.
Adult games are a nieche, like any other. You could easily ask, why so many people want horror games - and those are played by far more people than adult games. Or why people want retro graphics. Or kinetic visual novels. Or idle games. Or video games in general.
One can make an argument against any nieche of games anything.
If it is not your cup of tea, you will not understand it and it will bewilder you from the outside. That's true for just about any recreational activity. Collecting stamps comes to mind. Or something more controversial: playing war games. Be it table top or as a video games. Why do so many people want games about war? Why are tv shows about murder so popular? Why are stories and drama about love and romance so popular?
Oh, and yes, pornography is appealing. Even among the oldest prehistoric depictions you will find porn. It stands to reason that a topic so prevalent in human behaviour will have games about it.
There is games about war, but people question games with porn. That's what's wrong in all these discussions. There is "innocent" Civilizations game series that will have you commit genocide. For fun.