The letters underscored Wikileaks exposure of a corrupt primary process and decades of corruption
The day that Comey released his second letter stating that no new emails were found, I wrote the following article, Trump will not lose ground over Comey's announcement, may gain in MI and PA. In summary, I wrote in that article that simply raising the issue of Clinton's corruption, even in a light that was positive with respect to one particular bad act, hurts her. This was true because Americans had decided what they believe with respect to Clinton's corruption, and most thought she was corrupt.
Even many Democrats who were voting for Clinton were doing so in spite of their belief that she was corrupt. The fact that the DNC and the Clinton campaign conspired secretly to defeat Bernie Sanders surely provided more than enough evidence for a great many in the Democratic party to conclude she was corrupt.
Comey announcing that no new emails were found sounded to many of us who have concluded that Hillary was corrupt like another example of her escaping justice. She hired five of her closest aids in dual roles, both in their named role and as her attorneys. This is a move worthy of a mafia boss; it stinks of corruption.
Comey's initial recommendation against indictment, that expressly labeled her as reckless and indirectly dubbed her an obstructer of justice, brought Hillary's polls down and allowed Trump to take the lead in several polls. In the same way the two letters late in the election achieved the same political impact of reminding voters that both
Clintons skirt the edge of legality and ethics as a matter of course.
Clinton faults Comey for suggesting she did something she didn't do, but it's what she did do that hurt her
In yesterday's New York Times Clinton is quoted as saying, "our analysis is that Comey’s (first) letter raising doubts that were groundless, baseless, proven to be, stopped our momentum." The Clinton campaign also believes the second letter hurt her because it reminded voters, particularly white suburban women, who were already distrustful of Clinton about the email scandal, and that reminder put enough of them them over the edge to Trump to defeat her.
While Clinton sees this as a key unfair development that led to her loss, one looking at the overall campaign objectively would see this as an example of a fatal weakness that existed because the media let her skate through the primaries without any real scrutiny.
Had Clinton received even ten percent of the close attention from the press that Trump received, she likely would not have won the nomination. The Democrats pushed her to the nomination by rigging the primary process as much as possible. She enjoyed the virtually unanimous support of super-delegates. We know now that Donna Brazile was feeding debate questions to the Clinton campaign.
These letters were released against the backdrop of Wikileaks showing a deeply corrupt Democratic party. Wikileaks demonstrated that Clinton was surrounded by people who trashed their fellow Democrats in private and held Americans in low regard. Wikileaks demonstrated that favors were traded for donations to the Clinton foundation.
Any development that raised the issue of her 33,000 deleted emails, which appeared to any objective observer to likely evidence a scheme of pay-to-play corruption involving the US State Department and the Clinton Global Initiative, was bound to hurt Clinton because of the storm of corruption swirling around her, not because of any suggestion that she did something she did not do.