I saw people say things on the internet (so it must be true) that Game Freak's passion project that the A development team is on is Little Town Hero, and the B Team is on Pokemon Sword and Shield just treating it like a job.
I'm generally fine with things like Mega Evolutions and Z-Moves and generation-specific traits or features not being in the game, and maybe even region-specific forms, but every version or generation should come with eventual access to all Pokemon and/or backwards compatibility with the previous generation somehow.
Tbh I bet they were taught this by Sun/Moon. Sun/Moon didn't have the National Dex, you couldn't trade with X/Y even though it was the same platform and you had to pay for the Pokebank instead. They'll probs make you pay for DLC Pokemon packs the same way you do fighting game characters, or a National Dex or something.