> look messier
I agree.

I know some roads which became worse, for example https://www.openstreetmap.org/way/366085036 was probably good in past, but now it is not.

I hope apps like https://github.com/streetcomplete/StreetComplete can use such tags to ask to update such information when 2-3 years passed.

Also, theoretically, auto-checkers can just check when tag `smoothness` was changed, without additional tag `check_date`, but I've never heard about such apps.