Right , there's allot of less than ideal listening spots with many P.A.'s too close to the stage you may not hear the full p.a. mix or get too much subs,
too much to one side you get the things panned to that side, but does any mixer mix in mono ?
Stick your head in a real piano and it's stereo , move 100 ft out and the piano is mono and the room sound is stereo,
I run a stereo 4x12 cab just to get a fuller texture, try two amps one with tremelo and the other without it feels like stereo even though nothing is panning between the two
Nothing wrong with stereo you just may need to tweak , make sure FOH has a strong stable gtr, and you have something satisfying