Rather then just grass then will cover the soil again over time, make all the soil/ground/surface dynamic so you can plant a tree which dies in sand, everything plowable, fertile soil could be used for farming. Not used then grass grows back unless it isn't fertile at all. Also tiles walked on very often should turn into a sandy path or something, lowable too but less fertile.
Am favouring the original feature entirly and was the reason for me to register.
Unlike the seeds for grass, it gives more realism since nature can't be cultivated as human beings like to think too much. That my humble opinion.
Thanks for reading my suggestion.