I understand your concern about music styles. I also wish that more styles and substyles could be available in iReal.
There are a bunch of Latin, reggae, R&B, pop, rock sub styles also missing or incomplete.
It can be a real challenge for the developers to satisfy everyone!
I think that creating and improving basic styles that can work over a bunch of other styles is the way to go. Maybe also adding a few options to double the tempo, measures, to choose between arpeggios, strumming, pads, short/long chords, moving accents and pushes, etc, would give more choices to the users.