This comes up with cars all the time.
What really matters is what happens when you're standing in the showroom with the cash in your pocket.
For all the internet talk of "I'd definitely buy a new [whatever] if I could", when you're about to hand over a substantial amount of money, all the romance and optimism suddenly disappears and you choose the new bike/car - you know, the one that does everything better than the old one (except look good).
How many of those repro Maicos do they sell in a year?
Even if they could mass produce them and drop the price to the same as a new YZF, how many more would they sell? How many people would plonk down $11k for one, instead of the same money on a 2017 YZF?
How many people bought new 513 CZs, when they were available? How many sat unsold until they were heavily discounted?
The Lazarus models only work when the factory screwed up and killed off a bike that was still competitive in the marketplace, and replaced it with something inferior: think KLR650, and um...