Since different patches of grass in a particular route can now have encounter rates, that could allow a lot more Pokémon to get squeezed into the game while still keeping gameplay reasonable. If you made each individual patch have a 40+% encounter rate for a different Pokémon, it gets a lot easier to add them all in one world without requiring a lot of 5% searches. Adding encounter rates (even if vague) to the Pokédex location function would increase the usefulness of these designed encounter rates.