Most of these people are probably just looking to create an image for themselves rather than find genuine artistic expression. However, I think that you bring up and interesting point about riffs. I guess it just depends on the sound you feel like listening to and the role that the guitars are meant to play in the music. Riffs get much more important if the guitar is meant to be the lead. However, some bands, like Paysage d'Hiver (at least what I have heard) make the guitars take a more atmospheric rhythmic role while synths and vocals take the lead. His guitar work consisted (to my ears) of only a few simple chord changes, however, it was nevertheless good in the context.