What bothers me is that the claim of dexit as an inevitability is horseshit. This isn't some third rate lesser IP, this is one of the most prolific and highest selling franchises of all time. And before someone pulls the card of how the games sell a fraction of the merchandising, the main series is still placed on a pedestal next to Mario for a goddamn reason.
Yet it's like they went out of their way to put as little effort into SWSH as possible even though the dex issue could've easily been solved in a plethora of ways. Giving more time (not delay, clearly too late at this point, but space out the releases for fuck's sake to give the devs more time to actually polish things so we don't get N64 trees), hiring more people that actually know how to program because GF still can't code for shit (reminder that the extra trip through Kanto wouldn't have happened without Iwata swooping in to save their asses, they've always been awful at this), patching in the missing mons later as you've said, or hell even adding them all back in the subsequent games of the gen, and other potential solutions.
But no. Instead they divided their already small team for a group working on triple A titles in half, gave priority to a game nobody's going to remember just like the rest of their side projects, and instead of even attempting to appease the angered masses they essentially said "This is how it's going to be from now on, fuck you" as a response. What an utter joke.