The issue is that almost all the combos in this game is nothing but 1,2,3 combos. Some goes 1,2,3 other 1,2,3,4. 1,2,3,1,4,5... Even DNC with it's proc based combo ends up with 1,2,maybe 3, maybe 4,1,2...

There just isn't much variety in how the classes are designed.