The way it works is the former landowner agrees to lowering the value of the land (or even to sell in the first place) only if certain conditions are met by the future landowner. The benefit to the future landowner is lower cost to purchase or just the ability to purchase in the first place. If the current owner no longer wants to abide by the restriction, then there is appropriately some work to be done to revise the deal.

Why wouldn’t it make sense for me to sell half my land to someone only under the specific legally binding condition that they don’t turn it into something I don’t want to live near? Especially if that person explicitly and knowingly agrees?