I think comunication before a song is played comes up alot especially if you have never played togeather before. Intervals are explained by such words as the mighty modes, is it major you want or minor? is there a turnaround? Are we just into power chords? These questions I would like to have answer to or told before we play. I noticed most ear players do not know the basic chords for a major scale like the Maj, minor, minor, major etc.
I do agree that there are those that can blow a person away in their playing but I find they cannot play well with others if faced to something new. The therory training gives one a head start to say.
I spent years putting new songs into bands I played with that could have been done much sooner if I had interval and basic chord structure training. We were only a cover band so the rules were simple.
Its funny how one can finish a course on music that you really though was good then wonder why to took it. One really does get something out of it but the nature of our desire to learn goes on to a higher level after each lesson. Give yourself some credit. You may be suprised to know others want to play like you!