>>58034313
Johto had fewer artists and a single artist would do multiple maps while in Kanto pretty much every single one was done by a separate person and most of them don't seem that experienced with pixel art. There was also a lot of clashing pixel styles while everyone in Johto went with mimicing the GBC Pokemon artstyle.
There is a guy doing all of Kanto by himself, anima_nel, who so far has done a better job than the Kanto redrawn