It's so pilots see the entire wind farm as a single entity and can interpret what they see and understand the extent of the wind farm easily. There is a pretty good study you can read on this:

https://www.airporttech.tc.faa.gov/DesktopModules/EasyDNNNew...

As to community impact, radar-activated lighting is an approach that is being used in places this is a concern. It allows the lights to remain off unless there is a plane within the envelope that requires the lights to activate. It's expensive though.