They demonstrate subterfuge, lying
The emails we've all be pawing through for the last several weeks (not just Podesta's, obviously - Clinton's own, as released by the FBI and State in as absolutely slow a manner as they can muster, when those should have been FOIA-able records the day she left office) demonstrate that she was lying under oath before congress. The bulk of the emails, yes, simply show that she and her team lie regularly to their supporters and the voters, on almost every matter before them. But what matters is her fictions surrounding her provisioning and use of her home server to do official business, and her destruction of records after being subpoenaed for them by congress.
I don't really care about the rest of it. That the (now) head of the DNC was just caught red-handed providing Clinton with a verbatim debate question in advance of the event (and, of course, now lying about that) or a hundred other little behind-the-scenes bits of tawdriness and sleaze is indeed just typical politics. But lying before congress, destroying federal records, and playing fast and loose with classified material (in a way that would prevent anyone else from ever holding a federal job again, and possibly landing them in prison) actually matters.