I have generally been meh in reaction to this as a scandal. In so far as I agree it is a scandal, there is that. But it also does not present much useful information for me. There were a number of reasons I was not very moved for or against Clinton.
It was always to my mind extremely unlikely she would be prosecuted or charged with a crime. High government officials are rarely held legally accountable for their behavior. David Petraeus essentially did the same thing. He in fact deliberately leaked information, something which would be hard to prove in Clinton's case, and only got probation and a fine. There were numerous scandals and public officials under investigation during the Reagan administration. Very few of them went to jail; one was a cabinet official convicted of bribery involving public housing projects and building contractors. Agnew was convicted of tax evasion, but Nixon was pardoned for Watergate. Albert Fall was the first cabinet official ever convicted of a crime while in office and that took until the Harding administration and Teapot Dome. And so on. This makes no statement of whether the legal system should be more involved in the accountability of public officials in the executive branch. It's a statement that they usually aren't charged and convicted when something sketchy legally occurs, and that any expectation that would happen here should be tempered by the knowledge that it hasn't happened very often. As to why it does not happen more often.
a) It can be really hard to prove an actual crime was committed deliberately. Bribery for example has to usually show there was some significant political favor purchased with the bribes. It isn't as simple as showing that money moved from point A to point B. These are rarely cases involving direct physical evidence like a murder or robbery that can be examined separate from the case itself.
b) Justice department officials and public executive officials, like local police and prosecutors, more or less have to work with each other and have strong incentives not to rock the boat too much where it concerns a high official who if they screw up the prosecution and gets off, then is likely to still be The Boss. And probably will not be very happy with whomever tried to grind an axe and failed.
Without a legal charge, there was little probability that it would have a major impact on the campaign. As a scandal it largely fit the processing of how many people already saw the Clintons (both Bill and Hillary). This is more a statement about us than it is about her. If people already saw her as hypocritical or duplicitous, then behavior which appears hypocritical or duplicitous simply reinforces the existing narrative. Many people already held this view of the Clintons and of Hillary in particular. This was not changed or altered in some fundamental way such that it actually matters in campaign horse race terms. I generally see coverage to the contrary as media attempting to get attention for something rather than reporting on something new and interesting. Such as any policy shifts she has made, and proposed to make, and whether those will be good for the country/world or not.
As a statement about her judgment it says very little. A more concerning feature of judgment is her assessments of waging war in Libya. Without a probable long-term campaign to re-stabilize the country after deposing a ruler, or risking any long-term diplomatic strategy for getting China and Russia on board if a more significant foreign government/dictator actually needed to be deposed, like, say, Assad in Syria. The Benghazi "scandal" has largely ignored this question during investigation, most likely because many elite Republicans favored intervention in Libya, much as they favored intervention in Iraq (as she did too). The email scandal meanwhile has occasionally been linked into questions over her support for NSA metadata collection, opposition to publicly available encryption, continued processing of far too many government documents as classified or other attempts to keep them from public view, and so on.
These to me are the far more important questions of her judgment being in error as these potentially negatively impact the civil liberties of millions of American citizens and residents, something a President has enormous power and sway to do. Likewise pushing for an ill-advised bombing campaign for the purpose of regime change in an unstable area without likely stability in the form of new leadership (which is judged in some way morally superior), seems like a poor judgment. The bigger picture seems more important than whether or not some sensitive documents were hacked because they were improperly handled. That's more or less par for the course right now, in my estimation, because that's kind of how the internet works right now. Documents will be hacked if someone wants to hack them. Or leaked if someone wants to leak them.