My last digital camera was a 5DMkII. It was 'fine,' but i can't recall an instance where i had a film scan or raw digital file that i thought was too large.
I think most of us buy equipment based on potential. The potential of the imaging chain and the potential that it'll be used in an ideal circumstance to yield an ideal image. That we rarely, if ever, actually get there is sorta irrelevant, isn't it? I think we're in a state of paranoia that we won't be prepared in that situation.
I know i have a lot of images that could be improved by some technical means, either by equipment or by technique. I also feel that i buy equipment at a certain level so that i can't use that as an excuse when something fails, whether we're talking about photography or tennis or whatever.... But, the fact that i do fail only furthers my interest in 'better' equipment.
That all said, there's always a 'sweet spot' as it relates to cost and convenience. We could have all achieved sharper results with an 8x10 camera than with 35mm film. We can get sharper results with a medium format digital back than a Canon 5Ds. We do what we can with the more realistic setups.
I want either a 5Ds/r or a Sony A7IIr. I want 40+ MP. In five years, i'll likely want/expect 75 MP. It wasn't that long ago, relatively speaking, that 6MP was "good enough for a double-truck magazine spread." If you told a photographer he could be shooting with 24MP at that time, you'd likely have been laughed at. Where does it stop? Where ever computer processing and storage make the MP count unwieldy. Other than that, it's just storage space, and not much different than keeping binders of negatives you'll never print, just because you only get one 'keeper' on a roll. There's going to be 'waste' in the process. And, even though this type of waste is now really about how large you want to print, i want the ability to print large... at some point. 250MP seems nutty, but there are two things to consider: someone, somewhere will want and use it; and it's a demonstration of technical prowess by a manufacturer. Bugatti makes a car that'll do 200+ MPH, despite the fact that no one outside of TopGear will get it up to that speed.