It's important to keep in mind that this "careless" assessment not only carries no legal weight, but was entirely inappropriate to publicly make. As Matt Miller - a former Department of Justice spokes-person who says he's voting for Hillary - succinctly just said on MSNBC: making such statements is not the FBI Director's job and therefore not appropriate. The biggest wrongdoing pertinent to Comey's statement about Hillary being "careless" is not about Hillary, but that Comey went way beyond his job and gave a non-legal opinion. What law, exactly, did the alleged "extremely careless" break?
What the FBI is supposed to do, and has done in past cases like this, is either announce an indictment recommendation, and say why, or no indictment, and leave it at that. There is no requirement for the FBI to explain why there will be no indictment. Indeed, explaining why, and commenting on what was uncovered in its investigation other than evidence that is legally actionable, is nothing but sheer political grandstanding, and is itself worthy of reprimand.
Or maybe kowtowing would be the better word than grandstanding. Apparently the GOP and most of the media have brow-beat the FBI Director to the point where he felt he owed them an opinion. But that's not what he was appointed to do.
Meanwhile, Hillary has said numerous times that she would not have used a private email server knowing what she knows now. It was poor judgement, made eight years earlier and less sophisticated in our digital age, but the FBI's year-long investigation could not find even a single instance in which any state secrets were actually leaked, or anyone's lives were endangered or compromised. That should be the story that's being reported.
And Comey should stick to his job. The FBI Director has more than enough work to do in our dangerous time, and should not waste his and ours with inflammatory statements that go far beyond his purview.