LogFAQs > #963592805

They actually werent limited
they had too much space left over so added in Kanto

The issue that the first set of games had a forced fucking maze with teleporters tho the trick is you only need to use one teleporter ever
g/s/c was much more liberal in making most of that side content. Same with seafom islands basically being optional but pushed heavily as the way to progress and then oh hey presto you could have just gone there from pallet town

all in r/b/g/y is just 'long' due to poor pacing and purposely forcing you to double back quite often.