>>58221592In every other game, water routes are considered the worst routes. They have little Pokémon variety, they need to be wide and open, the Trainer classes are nearly all Swimmers minus the odd dock with a fisher, and every single tile is a potential encounter, as if you were walking through a cave or tall grass. The encounter frequency may be lower, but when every battle is pointless, battles become a useless mechanic that need to be negated with repels for the game to be bearable. It's not even like those long gauntlet routes where you're steadily worn down and have to debate whether or not to turn back.
Diving exists, yes, and that's decent, but it can't do the heavy lifting required for 17 water routes to be fun. The best parts of the Hoenn's water routes are the parts that aren't surfing. Your nostalgia leads to bias.
