Also because of the sequels being all connected to each other, along with the extensive codex. It's fun for people to discuss potential sequels based on throwaway lines about some planet you just scanned. I mean, most games can be distilled by one aspect. Call of Duty has noobtoobs and online multiplayer, Fallout has OH MY GOD I JUST STAKED A MUTANT TO DEATH and so on. Pokemon's niche is the meta.