Okay, it certainly didn't help, and I think he had no legitimate reason to time it that way, but I think that Clinton has no one but herself to blame for the loss. One, the email fiasco was absolutely a stupid thing to do, regardless of whether it was criminal or not. Two, she didn't really campaign well, often just letting Trump run his mouth (and let's face it, his worst opponent was not Clinton, but himself, but you couldn't count on that to win), and she allowed a very negative view of her stand in the mind of voters. Calling Trump voters 'deplorables' just galvanised them. She underperformed with the people whom President Obama won over, including groups in traditionally Democrat strongholds. A lot of people either voted for Trump, a third party, or stayed home, because they openly disliked her. It's unfortunate that, at the end of the day, this election wasn't really based on issues so much as it was an unpopularity contest. While I disliked Trump far more, I did not like Clinton, and resented feeling like I had to vote for her to vote against Trump, especially given things like how the DNC favoured her over my candidate, Bernie Sanders, and the media's role was terrible, too.
Hopefully we'll have better candidates, next time. To be honest, I think the bar was pretty damn low in the general election. But any new candidates should take this year as a cautionary tale and learn what not to do.