What is your point about Amb. Gration? That he had at least five other bone-headed practices, so violating the Federal Records Act is not really an offense worth caring about? Even if true, does this help an official who presented Russia with an "overcharge" button for diplomacy, who wanted to obscure the events leading up to Benghazi because she pretended to not see what difference it would make to understand the truth, and who flagrantly violated State Department policy while her immediate underling was persecuting an ambassador for violating that same policy?
Perhaps Colin Powell also violated the Federal Records Act. State Department policy did not officially require use of government email servers (except in emergency situations) until the year he left the office. If he wants to run for president, there should certainly be a public debate over what he did or didn't do with regards to that. However, his primary defense -- that most of his emails were sent to government addresses -- is also Hillary Clinton's primary defense.
I did not directly address your facile arguments about what a foreign government would want from a Cabinet secretary's email because I thought the holes were so obvious: Hacking her server would give far more information than they could capture from a single conversation in her house, it is easier to do deniably, and at any rate the undeniable breach of federal law is in failing to put federal records in proper custody for preservation and oversight. For high-level officials, mishandling classified and SBU information is a real risk (and what the IGs here want to be investigated), but is not such a clear violation.