>Surely this depends on a lot of societal/economic factors (i.e. a "you do it or don't eat" job market, say) and the evolution of the form factor (size/weight/quality/individual ergonomic options).

I think the former is a way bigger factor than the latter, here. Even on the old first-gen HTC Vive, I was entirely comfortable "working" 8+ hour days wearing one (coding, painting, and sometimes gaming). They've also improved massively since then in weight, weight distribution, softness, and heat management.

I'd say the biggest detractor is how they look (and some other smaller factors like not being able to feel "safe" cut off from your surroundings, but all major VR companies are working on that, too). However, how they look ends up not really mattering much if you're VRing from home, where no one can see you.