The largest I ever printed was poster (40" by 30"), and a handful of those at that. I'm an effing amateur, lets say I needed 18MP for that. I'm impatient, so after half an hour framing on a tripod, I still cropped a couple of MP. So even on the rare occasion I go big and compensate for my lack of skill with what is, for my needs, an overkill camera, I barely scratch my 5DmkIII's resolution.
I've looked left and right, and say that covers what 999‰ of camera owners need, if not 9999‱ of them.
I don't see why the niche within the 1‰, or 1‱, who actually need >30MP (crop wildlife & print large, ads on billboards & walls five stories high, etc) would be posting so much about it on forums. My guess is they have the manufacturer's ear anyway.