You’ve never spoken a truer word. But add-ons depend on the foundation that the sim is. So far we don’t even have a complete SDK or a working set of basic features. Things here and there are getting broken every time they update something.
Besides, add-ons are being developed by different people who are not always concerned about the compatibility issue. And the heavier the add-ons are, the more they intervene into the sim core, the more is the potential for instability and problems. We’ve discussed A2A and HiFi above. Both have to work around the sim to make their technologies work, not with it. Helicopters already have their own flight dynamics engine for MSFS (in fact, there are several of them already). How many external weather, FD, camera, and other engines do 3rd party developers have to build to make the sim palatable? And how many will it take to crash it to desktop on every launch since it is doing it already pretty well?
By the way, it’s not ‘homages’ to FSX in MSFS, it’s whole huge chunks of code borrowed from it, and MS/Asobo has never concealed this fact. And there are reasons to it. And if you ask me, they aren’t good. Regarding homages, many solutions in MSFS seem to be borrowed from X-Plane rather than from FSX.