I read earlier that having generators close to your house or beds where settlers sleep decreases your overall settlement happiness; wind power doesn't do that.
I also read that there was another mechanic involved with generators that was removed before release: fuel. You would actually have to refill your generators with fuel, and keep a constant supply of fuel. They removed it because that sounded fucking way too tedious and retarded I'm guessing.
If you want to build a green farm or a non-polluted / quiet farm there's plenty of mods out already that allow you to do a ton of extra settlement stuff, like build way more stuff, expand the limited scope of settlements, actually makes wind power useful, other shit.