>>32511210I think Megas, regional forms, and UBs are efforts to limit the pool of attainable Pokemon that can be put in games.
That way, as the total mon count increases over time (which they're also making efforts to control with relatively few actual additions), they're less obligated to insert some mons into the game and basically oversaturate it.
Specifically with Megas, they went the route of item dependency. As we saw with Gems, there is the possibility to remove items between generations/games. That is to say, they don't have to necessarily 'retcon a Mega out of existence' but just claim that the stone is unattainable for one reason or another. And Megas don't count toward the dex as I acknowledged so it's not like a real loss of a mon. I think it's a smart approach to gauging public reaction to new ideas while also controlling the population size of the number of mons.
