We pay less for gasoline and get something that ( occasionally ) resembles service !
I have found during my occasional travels through New Jersey that you do not get any additional services such as windshield cleaning or oil check. (Not that that would be a justification for mandatory full serve even if you did get those services.) In fact you sit around waiting for the one or two attendants servicing 10 cars to get to you. If you want to get faster service, then begin to pump the gas yourself (pretending not to know that it is full serve) and watch the attendant come sprinting over to you yelling that you are not allowed to pump.