I think it encourages you to relax and not focus on getting everything right away, grass doesn't erode as much if you just walk.
I know for some of my friends, the game becomes a competition of who can get the most cool stuff. One of my buddies had a dessert in about a week and im like "cool, you have all this stuff but your town looks like ass".
I believe it brings a balance to the game. I found myself using the same paths and roads to minimize the grass erosion., and walking a lot more.
but, I agree there should be a way to restore it, either by watering or maybe this game has grass seeds, maybe the gardening shop sells them.
btw I just saw the nintendo direct, there is so much in this game!!!!! KK DANCE PARTYS!!
I doubt there is grass erosion, it's just that the grass textures have become more advanced looking and detailed. It's not just thick grass all around, there are more dirt patches, and even in normal grass, you can tell there is ground beneath it.
It's a different direction for the series, but I'm liking the look and feel of it so far.