I think he finRAB more success in his instrumental works because everyone and their brother will, at the very least, begrudgingly listen to Colma, and Sketches of Spain (for Miles) off of E.T. is on of the better tracks he's done.
And lest someone confuse success with money, I think he gets his point across better without worRAB. Giant Robot and Monsters & Robots were fun albums, but the various characters are more the some folks can handle.
I actually enjoy this concept and I'll go check it out even if there are 9 minute solos.