As far as how many speakers you're using, who gives a crap? That's personal choice, let the music stand on it's own merit. 
I listen to both MC and stereo music, I do give a crap and I'm sure there are others. I especially care when referring to older music that was recorded and mastered on analog tape. Without the original single track tapes, which usually no longer exist, they have to use the master tape (assuming it still exists) to create the MC master. But virtually all of those older masters are in stereo or mono and they often sound like shit when re-mastered into MC. Also, many older recordings were often laid down with all of the instruments and even the vocals on a single tape. Re-mastering those into MC is almost impossible, you get stupid effects, like lead vocals coming from the surrounds.
A perfect example would be
Sonny Rollins' Saxophone Colossus, one of, if not the finest recording ever made. But it was recorded in mono and every single stereo re-master I've heard has sounded like absolute garbage when compared to the original mono. However, there's no accounting for taste, because some people do actually prefer the stereo versions.
OTOH, digital recordings or in cases where all of the original single track analog tapes do still exist is a different situation. It is much easier to manipulate those and separate out the individual instruments and vocals. Those can sound very good in MC.
