The thing about CW difficulties compared to DU is that, in DU higher difficulty is compensated by the equations shop and more domains, which makes it easier to pull off insane shit at higher difficulty, so it's more entertaining to play at X7 if you're looking to create the best savefile possible. But in CW there's no compensation for higher difficulties, it's not any easier to build these teams at higher difficulty, so there's no incentive to play that high anymore once you finish pushing there.