I may have written this before, but Clinton's behavior at State, at least as described in a recent summary of the aide's deposition, makes sense to me. Bottomline: bigshots don't give a damn about systems and legalities. It's the job of the bureaucracy around the bigshots to adjust the systems and legalities to what the bigshot wants. Clinton wasn't going to devote any brain cells to worrying about the security status of what she writes or reads; she was focused on the content. The exception to this is the initial discussion of the private server and Blackberry. Then you're expecting a civil service bureaucrat to tell the big boss the rules and how to get around them. Won't happen with many bureaucrats.
The big mistakes Clinton made was on insisting on a lot of close personal aides (Obama let her have more control over State personnel than is usual) so no one to say nay and on insisting on total control of release of emails.
The big mistake we the public make is expecting that laws are self-enforcing; they require bureaucrats to say nay.