I don't understand how it's an excuse that the current version is new or newer than X-plane? Either this is not actually MSFS but just a new game that sells by using (abusing) a known name or it is MSFS that has roots back to the 80's. If it's the last then it is clearly moving backwards if it has missing features and less realism. The logic that every new release is starting from scratch and isn't comparable to the old version is strange. Even if they throw out all the code and start coding from scratch MSFS is still not some un-comparable game to the last release.
To take it to an extreme: If Adobe started from scratch and released a new shiny Photoshop that looked good but had the features of MS Paint would people see it as moving backwards or "give it time, third parties will re-add missing features"?
In case of third party content I think it's a valid point. X Plane did not have these add-ons when it was released, they came a few years later. So it's not that strange to give MS FS a bit of time to catch up in terms of third party add-ons.
Missing features in the game itself can't be excused that way, but guess what... X Plane still after many years also doesn't have a good enough for training built-in simulation of a GPS.
To take it to an extreme: If Adobe started from scratch and released a new shiny Photoshop that looked good but had the features of MS Paint would people see it as moving backwards or "give it time, third parties will re-add missing features"?