I'm with you there. Why not just think in terms of altering the major scale rather than altering modes of the major scale. That's another layer of complexity I don't need, and too many steps for me to do in an instant.I can't say "we" need theory, but I can say that "I" find it more than quite useful, possibly because going to music school brainwashed me in that regard.
While studying with Jerry Coker I was indoctrinated into the George Russell way of thinking. It was put across to me as a method of ear training that I would eventually discard, just playing what I thought sounded right. I said "why not just realize that on the altered dominant the 5th, 7th and 9th are altered from a major scale instead of thinking of lydian augs?"...
I knew Jerry Coker when he taught at UT. He even played (piano) at my wedding back in the 80s behind my friend, one of his students, on sax. For a sax player, he was an excellent pianist. I've got his books and still refer to them. Never did quite finish working all the way through any of them though, just the bits I was interested in.

