I'd put it on a lower rung of the ladder but yes, definitely still important for it to be an overall 'great H-game' as a package.
My way of seeing it is that if the game is bad, at least I can still enjoy great art.
If the art's bad, there's no reason to play the game - I can find a different game with good porn if I'm horny, or I can play one of the many many none-porn games on my to-do list if I just want to game.
Counterpoint : Rance series games. The porn there is usually mediocre, but the games are hard carried by the gameplay and/or story
Just a few steps more - and you will reinvent old terms "Balance" and "Good gamedesign".
Good game can be better with some hot scenes, bad game will not. But if all that game has - is the scenes, the game will be too boring to play.
Then there is third ancient secret - "Gameplay loop" and fourth - psycological thing "efforts expended and reward received". If there is too much efforts needed to get reward(in our case - new sexy scene) - majority of players will abandon the game. There is a few platformers here with absolutely inadequate difficulty curve and for some
mysterious reasons they are abandoned.
If hot scene is too easy to get - then there is no interest in playing, just occasional fapping sessions, which tend to get boring(coz you can just visit phub or something). That is common problem for another big chunk of "games" here - especially with "have to lose to see the scene" type of "gameplay." They are boring too, because there is no actual gameplay loop, and when you have to loose to get reward(new scene) - it is not a reward anymore. But usually devs are just too stupid to do something about it. So that kind of projects tend to stagnate and die slowly - they have no skeleton(story, gameplay, etc.)
That's why gamedesign is not an easy subject.
Thats why the majority of successful games hare have all of the main component - story, gameplay loop, some challenges and then - rewards. Another mystery! But then again - there is greed factor - why to make a game, if one can milk patrons. A dream come true for many wannabe porn-game-makers. Problem is - in time they tend to stagnate too and when milk stops - suddenly no one want to give mone to degenerate shit-of-a-brain liars anymore. Difference is in time limits.
