I don't know too much about it as I've never paid a ton of attention to the lens as I'll never buy one but I think the upgrade to the 85L II was much less drastic than some of the other upgrades. Were there any external changes? I think it was just new coatings on the optics and a different drive ratio for the AF, no? Correct me if I'm wrong. But if I'm right, the 85L is still really a 90s lens.
Not sure if I agree with you at all on this (other than doubling the price, that's sure to happen). Traditionally, I think 35mm is much more common than 24mm and probably second in popularity only to 50mm for prime lenses (possibly even more popular now with crop sensors). And again, traditionally, 85/90mm and 135mm are both much more common than 100mm. Actually, to me, 100mm is kind of a weird focal length and it isn't necessarily one that I would think to buy other than the fact that it is available as a macro lens.
So, ultimately, I think 50mm is the most popular lens but I think 35/85/135 is a much more common combo than 24/50/100.
True 35mm was definetly more common than the 24mm before 1980 but the zoom came into fashion and replaced all the primes for all but the pros and few who demanded the best image quality. 35 and 50 are probably more common but if canon were to SELL NEW lenses they obviously started with the 24 before the 35. I think each is equally important but for different reasons.