And the requirements for O-1 aren't even that difficult. I know people who are frankly not exceptional (not mediocre either, though, of course), but have worked with lawyers to systematically fulfill the requirements of the O-1 visa. It does take time to do, and I assume the legal assistance isn't cheap, but I think a lot of people on H-1Bs who don't even consider it, could do it.

O-1 requires yearly assessment of the exceptional status though. You can hardly plan your life around a visa that is quite subjective in itself and may depend on the mood of the USCIS officer reviewing your case on that particular day.