No high ranking USG official should be using insecure communication channels, as it will inevitably lead to leaks that could damage the state (secret information).
What Clinton did was dumb, but no one should have sent her classified emails in the first place. If the people sending the 'classified' documents were doing it through the right channels, it wouldn't be getting to her email server.
From a human rights, civil rights, universal rights, and transparency perspective all USG communications, and communications of all government officials everywhere should be public knowledge available to anyone on the planet at any time. At the end of the day what we find is how much all of these people conspire behind each other's backs to screw each other over and get the upper hand.
If citizens are not allowed to do this for fear of damaging society and government, politicians should be held to the same standards. For fear of damaging human rights of non-citizens, their livelihoods, economies of other countries, etc.
It's funny how government does not trust anyone below them, and yet expects everyone below to trust them when we know that they do not do the right thing most of the time (tm).
What Clinton did was dumb, but no one should have sent her classified emails in the first place. If the people sending the 'classified' documents were doing it through the right channels, it wouldn't be getting to her email server.