First off, some consumers aren't interested on how the music sounds on their system, they are consumed about how OTHERS hear it on their system, from another car at a stoplight.
Second, they are compensating not for deficiencies in the mix or mastering, but for perceived deficiencies in their audio system. These will vary from system to system and you still need your tools to find the middle of the bellcurve of this aggregate "average system".
Third, I turn my visions into the best reality I can, because my expression is a higher priority than mass appreciation, because...in my opinion, the second can't come without the first... for long anyway, see "Milli Vanilli".
Fourth, I have a performance room adjacent to my main tracking room. Tracking room and both control rooms are set to mix and master from studio monitors, flat, accurate, average, etc. Performance room is for enjoyment and intake of expression. I EQ my own mixes there, to fit the room and my mood, and my current Fletcher-Munson curve. If somebody wants to pay me for expressing myself, they can alter it however they see fit, for the enjoyment they compensated me to purchase.
All that said...I do question the intellect and sanity of some listeners, just as I am sure they question mine! If this thread produces a huge selloff of equipment, market glut, and basement pricing, I might toss a few pennies at surplus inventory if you all pay shipping. TIA!