Full body scanners can be used as an effective tool to counter terrorism. It helps to ensure that no one enter planes have anything dangerous, or harmful on them making others feel more secure. It is important to stop anyone who wishes harm as soon as possible and if a full body scanner does that than it is effective.
While looking at all the TSA does, I think the full body scanner is the most effective. It might make people feel uncomfortable, but unfortunately the times have changed. There hasn't been an incident since these full body scanners came into effect, but that doesn't mean I think there isn't room for improvement. Right now, I'm not sure what else would work. We know bombs have been hidden in shoes and on the body. This detects that, and if that's what keeps us safe, so be it.