>>47948328If Red and Blue came out today you'd complain that this "PokéDex" feature obviously means you have to catch every species before you can continue. After all, the whole premise of the story is that this Professor Oak guy wants you to fill the PokéDex, right?
Nowadays it's easy to forget about the "fill the PokéDex" quest entirely, so fleshing it and adding more clear milestones is a logical change to keep it relevant.