People vastly underestimate how adding a few extra creatures increases their workload exponentially. Just try making an excel sheet to document every Pokemon's moves, stats, etc. Now try making an excel sheet keeping track of possible team combinations, movesets, etc. Suddenly adding new animations and features, becomes a herculean task. Oh, you'd like each Poke'mon to do a flourish animation after winning a battle? Ok then. Start animating a thousand creatures. Oh, you'd like a mode where you can pet your Poke'mon? Add 10,000 more animations because that mode requires each of the 1,000 monsters to have 10 different animations. What's that you'd like to introduce a new Dragon type move? Well, you'd better keep in mind that people can breed moves into Poke'mon that normally wouldn't have them. So you'd better do an excel sheet on that as well, and go about animating such things as Arcanine using Dragon Pulse. Now, what if we make Poke'mon an open world, epic in the next few years? Well that's 100 new animations for each creature. Most games only have 100 character models, and you people are expecting a game with 1,000 character models, Mario Odyssey level graphics, Open World, etc. Sorry, but ti's just not gonna happen unless they cut Poke'mon now.
For anyone that thinks they know how much work game development takes, I suggest they try it for themselves. I've been part of four different game development class projects, and things are never as easy as you'd think.
Even if Gamefreak expanded they still wouldn't be able to make the Poke'mon game that everyone really wants, because a game like that would put even RDR2 to shame in terms of scale.
