>>57896162It was clear they had a bunch of ideas they wanted to implement in those games, kinda like how they experimented with the formula during gen 5, but they ran out of time, so they ended up pushing only a handful of ideas they had and filled in the gaps with Kanto/nostalgia pandering. It resulted in gen 6 selling slightly more games at a bumped-up 3DS price, even though the content they ended up implementing required way less effort to develop than the changes they implemented in gen 5.
It makes sense to me that ever since then, logic follows that all of the mainline Pokémon games they would go on to make would rely mostly on gimmicks and a lot less on improving the scale and the quality of content of the games themselves. Granted, the content they used to optimize was already minimal, but gen 8 onwards it seemed like they completely gave up on trying to keep it presentable.