I have a theory...well, I always have a theory. I agree about muscle memory. You're not training just your mind to play - you're training your fingers as well. When I sing and look at the words, and it's a song I could probably sing just fine without the words, I mess up a lot. I think it adds interference. You not only have to concentrate on feel, but sight as well. I play fiddle and hardly ever look at either hand. When I started learning how to play fiddle, I did look at my hands, like you look at your right hand. You teach them what to do and give them more guidance until they've got it, then let them continue on their own.
One other idea - where you put the fingers of your left hand won't change unless the tune or chords change, but the picking pattern may. Maybe you want to keep the right hand open for change, and not commit the picking to "muscle memory" right away?