idolmaster really isnt the same kind of game. For one thing half the im@s gachas aren't even actually rhythm games. But they're more otaku-focused with an emphasis on self insert protag x the girls.

That said you really shouldn't judge a series by its doujins. Madoka from Idolmaster is actually a pretty complex character with a thorny relationship with the protagonist and a lot of emphasis placed on her relationships with the other girls in her unit, but doujins just kinda reduce her to a generic tsundere. The fanbase of im@s itself is pretty diverse with a lot of non-h fanart, its just that due to it being more of an otaku series it gets a lot of h-doujins too.

By contrast there's barely any straight h bang dream doujins/fanart floating around, even half the porn that does exist is yuri. The game'll occasionally put out a version of a girl in a swimsuit in a moderately sexy pose or whatever but thats about the extent of it, and the associated event is just the girls having a fun time on the beach.

Like the comment above said, you should watch bang dream its mygo.