You're absolutely right and things should work that way. But these are in fact political appointments yet their point is to give the member states a sense of entitlement. Once the voters have lost their confidence in the political party to which the commissioners belong, there's no reason for them to be there, as they really haven't been elected by the people. Moreover, they are unlikely to play second fiddle any longer, the temptation to stick to their own narrow agendas is just too strong. Keep in mind that these people are professional politicians, not technicians.