Quoted By:
Johto is only so great because it's Kanto 2.0
It came out while Pokemania was still in full-swing and was the first sequel game to the series, so there was already a lot of hype being put into. It added a lot of new features which were great, but that was complimented by the fresh coat of paint put upon what the first game created (As well as still being tied to the first game.) A lot of the new Pokemon introduced were new evolutions to existing ones (which there was nothing wrong with at the time) but even the completely new still felt like the first game since a good handful were originally intended for RBY and it was the original designers who designed the rest.
I can't imagine what Johto would have been like without the ability to go back to Kanto, because without that the game itself has a lot of nice atmosphere and personality, but it's lacking substance on it's own. It's also the only new region who banked on you playing the last game to understand the story and core characters, which is again, probably thanks to Pokemania around the globe.
