>>53375153More like because after Diamond and Pearl the only thing left to do was add gimmick shit.
Gen 1 = OG
Gen 2 = Day/Night (at the time), Held Items
Gen 3 = Natures, Abilities
Gen 4 = Physical/Special Split
That's it. That is the core gameplay of pokemon completed. After this you're just adding more mons and gimmick shit. This is combined with the massive technological upgrades that occured. Up until Gen 3 the previous game was absolutely archaic compared to the current game, Gen 4 had wifi/global connectivity so Gen 3 was archaic compared to it in that sense, but was less of a substantial jump in terms of UI and such. Gen 1-4 is pokemon from infancy to adulthood, no new advancement could ever match what occured over that span.