In my band we had both guitar players who had the big is best way of thinking. After lots of rehearsals that you couldn't hear the vocals at, myself and the drummer (YES the drummer) told them both they had to do something about the volume. Guitar player 1 changes his Marshall half stack with 4x12 cab for a Vox tranny amp that has built in FX (can't remember the model) problem solved for him. Guitar player 2 gave the "I can't get my sound at any lower volume" excuse using a Fender hot rod deluxe. He wouldn't use a pedal etc. Now I know money was an issue for him, but we didn't expect him to buy new amp or anything. I even offered to loan him my tube screamer, or couple of other overdrive pedals I have. All to no avail.
We had to get rid, not something the rest of us were to happy about at the time but, some players and from my experience guitarist a) think its great to play loud. I can't disagree but its just not practical. Will never take advice from the bass player (what do we know abut playing an instrument ! )
As some have said I think it is a historical thing with guitar amps, more so with my group as we are all over the age of 50 and if the guitarist you use big amps, smaller amps have only recently started to sound really good, but thats no excuse to sound crap.