Minority yes, but I am not in the 1% percentile that prints larger than 8x10s (because that tier is > 1%). There are several polls out there already on different photo forums that show people that print > 10" on the long side.
Also, you must consider the fact that it is the client ultimately that dictates the print size, whether it is from your online gallery that allows print orders, your employer, etc. That statistic is the most meaningful, since the client <> the photographer in many situations.
Finally there are articles that describe why more resolution is indeed better for noise and detail management, not to mention cropability, and multiple resulting images/compositions from the same image.
Resolution is useful for vastly more than just printing. Higher resolutions also provide "possibilities" to the photographer that may not be available to those that shoot with lower res cameras. Having had a 21 mpx and 18mpx was great, I can crop out nearly 1/2 that image and still produce an 8x10 (the other 99% of the vast majority of the world's population that own DSLRS
). I can take an image where there are 2 or 3 different activities or people in them, and crop out 3 different photos from the same frame, and still having something I can print 5x7s and even 8x10s with a bit of PP. More resolution is a good thing, as long as the manufacturer mitigates the other factors that might get worse. Is there a limit to when resolution is enough? I expect so, but I cannot put a number to that really.
If Canon made a 30mpx FF that had a great AF engine, etc, that would be a killer camera. Crop out an APS-C image from that and still have enough to print large prints > 8x10, yeah! The 5D2 is close, I tried it a few times, but it needs a bit more resolution yet, it is not quite there for what I shoot, and add enhanced AF and more points, and I will go back. 