I imagine that a lot of contemporary artists, esp. in a genre like hip hop, probably understand and anticipate that most listeners will be hearing their music with bass-heavy phones, and thus they factor that into how it's produced. So in fact for such music, listening on an absolutely flat pair of phones may be not how it was intended, and may be bass light for that reason. For example, I imagine that when the Kendrick Lamar masterpiece "To Pimp a Butterfly" was made, they didn't decide what levels were best for the finished work based on how it would sound on a pair like the ER4SR.