I think I agree with
Yareru 's point that part of the excitement on playing these games comes from having a reasonable amount of grind or challenge, so that it feels like a reward when you finally get to the sex scenes and you've no idea what they're going to be, it's a surprise.
When you put too much grind (or excessive plot, like walls of dialogue) the game becomes boring, when there's too little grind / litte plot, the game becomes too easy and it feels wrong, it doesn't "suspend your disbelief".
My favorite games are the ones that balance these well (Summertime Saga), very immersive, there's also some games that miss the balancing but have such great art/animations that it makes up for it.
But like NightMirror said, different people like different things, I can't speak for others.