It's also useful for when you want to tuck away into a corner and repair your tank, then jump back in it when you see a teammate coming near. Your blind spot is huge while repairing your tank so you need radar to see your teammates with dollar signs in their eyes ready to steal your tank. And sometimes it's actually someone to help you heal, so they will get points for repairing you if you sit in your tank. You get no points for repairing a neutral (unmanned) tank.