Well, they could've made Splatoon 2's data safe, but off course they make it impossible to save online multiplayer data, which is obviously more important than single-player data (unless Pokemon is involved).
Actually, not really.
But I really think they should at least save "single player" data in Splatoon 2. At least let us Cloud Save our level, single player progression, weapons, chunks, gear, etc. They can leave rank out of it, but let us save the other stuff.
I'd be fine if that were the case. They can leave rank, or any multiplayer metric out of it (which is really only ranked), but allow the other data to be saved so if the game does crash we won't have to start from level 1 again.
People can deal with regrinding for their rank if they need to, but losing everything is much more demoralizing. All your gear is gone, you have to unlock all your weapons again, etc.