>>43616170GF thought the switch was going to flop hard, so they put their effort into making a 3DS game after SM released, then shit the bed when Nintendo and TPCi demanded a game after the Switch had a great launch and continued to sell.
GF cobbled together LGPE in the hope that it would be accepted as a cute spin off for kids, but the more attention it got, the more pressure began to mount on them to develop the next game for the switch. They fucked up importing stuff over to switch development from 3ds development, shit the bed again and conceded that they would have to develop some shit from scratch, but just told everyone it was brand new.
After LGPE released, they were told "Konsuumaa rabu za obawarudo enkawantazo, putto itto in za gemu", and promptly shit the bed a third time. They spent the last few months before E3 building the wild area and implementing overworld encounters and overworld models, then realized that they couldn't do this in time to include every mon as they had originally planned, or make a good game, so said they were cutting down the numbers on purpose for a "unique adventure".
They more than likely finished making the game not long after E3, and began frantically working on the DLC and implementing the remaining mons to make them compatible with SwSh come the end of the Gen. Visually, the games aren't going to change until they do another remake or start a new Gen. I hope that now that they're developing the next games specifically for the switch from the ground up, the visuals will at least make sense when they are announced.
See
>>43616176 for the short version