I am obviously not Carenado, and I don't have any insights in their business except that I know Dan Klaue is a very nice guy and very dedicated, but I nevertheless can understand why at some place such business decisions become necessary. The more aircraft you have, the bigger the support effort becomes. This needs time and people who need to be paid regularly, at least if its a real business where people do that for their livings and not just as a part-time job with other (main) jobs securing their living.
With just a small fleet, you can handle this by developing and selling new aircraft models and doing updates and support next to the new developments. But the bigger your fleet gets, this gets harder. More and more time has to be spent on updates and support, and less time can be used for new aircraft. This is the point where you may need to charge for updates. And if your fleet is REALLY big (such as Carenado's and Alabeo's), and users expect updates even for the oldest members of that fleet, it may well be necessary to charge the full price, because that's the only way for getting the required regular income -- because while you are busy with updates, you can't develop and sell new aircraft. And X-Plane has the tendency to keep you busy with constant updating over years.
It's all not so difficult if you're doing this only part-time, as we do at vFlyteAir. We can still afford to offer free updates, because we only have a few aircraft, and we have other jobs as well, but even we feel that the constant need for updating is a bit ... straining, as it takes time away from working on new models (our only source for vFlyteAir-related income, if we don't charge for updates). If we hadn't our regular jobs, we probably wouldn't be able to offer free updates at some point, too. (First, we had more time to develop and could sell new models, but this would let the fleet grow, at some point leading to the challenge described above).
So don't judge overly fast about such business decisions. These are not evil people who are just out for a quick Dollar, Euro or whatever. It's sometimes simply not possible the other way. The alternative may be to drop support for older or less-popular aircraft and only focus on the successful ones.