"It's not a private landowner's responsibility to own and maintain his/her land for the "public good.""

I understand your point, but this is incorrect. There are many instances where a landowner has the responsibility to maintain his/her land for the public good. Building codes, for example. You're also required to keep minimal maintenance of vegetation to reduce fire and pest risks, and to prevent your jungle from encroaching on neighboring property.

A landowner owns the land, but it is not isolated from its neighbors, and having neighbors brings legal (and moral) restrictions on what you can do with your land.