It was supposed to be the great milestone of the franchise, the first, official, mainline console pokemon game. People have been clamoring for that since stadium, thinking about all the cool visuals and crazy things they could finally do once they weren't held back by handheld hardware. Games like Colosseum, XD, and Battle Revolution were teasers for the sort of stuff we could eventually see.

Then the hype season kicks off proper with the news that half the roster is now gone... but that it's ok, since that means the game's gonna have better visuals, animations, and balance! Then the game finally comes out and... visually and gameplay wise, it's an upscaled 3ds game. A majority of models and animations are the same ones they've been recycling since 2013, story's just as shit as ever, arguable worse since it doesn't even properly start until the very end of the game where you're railroaded through it. The wild area, the big selling point of the game, is just a glorified safari zone you can fully see in 20 minutes right when you get there at the start of the game. No other optional side areas, optional side attractions /facilities, nothing. You better enjoy admiring the safari golf course and the same raid battle (less fun totem fights) over and over, because that's the bulk of your game/all of your endgame.

In my eyes, the reason it fucked everything up is because it failed to live up to the hype/expectations. A good chunk of us were expecting a full and proper mainline console game, and instead got more of the same with a 480p to 720p facelift.
>"whatever, the game was perfectly fine, you're just ENTITLED"
Built up hype aside, the simple fact of the matter is pricetags/hardware set expectations. They charged $60 for this, they demanded the AAA price, as such, people expected the AAA treatment/experience, and objectively they fell short of it. Compare this to ANY other big budget AAA game on the switch and it falls short of all of them.