>>29269415They do change it up but not consistently enough that the archtypes don't start to blend.
At least 5 out of 7 Generations have a Normal/Flying Regional bird family
Unova and Aloha are the only regions that gave their regional bugs distinct identities outside the others.
Regional Rats are just plain Normal types outside of Kalos and Sinnoh.
Not one Pikachu clone has been able to make itself unique enough to not always end up being seen as one. Evan the ones that make it to competitive play still can't escape the label.
Fire/Fighting was loathed because it occured 3 generations in a row, and has created a stigma where a Fire starter LOOKING like a fighting type pisses people off.
Unova itself has probably one of the most reviled Starter trios because of how BORING they are, where funny enough all 3 of the starter types that generation people had used 2 times before, so it wasn't just Emboar competing with Blaziken and Infernape for idneity, but Samurott with Blastoise and Feraligator, and Serperior with Meganium and Sceptile
Ultimately, if Gamefeak wants to start Generation 8 on the right foot, it needs to put the most effort into the bread and butter archetypes they won't drop.