The USA, in memoriam: it was a nice ride while it lasted. My take is twofold, though both are arguably the same (the Democratic party establishment is horrible and just doesn't fucking understand US politics).
First, every presidential election brings out a lot of people who don't normally vote. Most of those people, like most of the electorate just vote for the same people/party they do every 4 years. However, lots of people (and it'd be nice if there was polling for this but I doubt it is possible) vote for "something different," or more accurately vote for the least political [seeming] candidate on the ballot. Obama was clearly that, so was Bush Jr., and also Nader. In the 90's it was actually Perot, though Bill Clinton didn't seem as much the politician as either Bush Sr. or Dole. Reagan was also a non-politician politician and may have been the one to start this trend. There isn't a candidate we've had that is less politician like than Donald and so they voted for him. (Note: in my previous diatribe on his supporters these voters mostly fall in the "stupid" category.)
Second, the Democratic party establishment has a tendency to get behind competent, capable, long-time party insiders like Hillary (in 2008 and 2016) and Kerry and Gore, that most of the electorate consider boring and/or corrupt (and, unfortunately, no, it doesn't matter that they are wrong). Kerry was not an exciting candidate and there is a very good chance Dean could have won. Yes, Gore probably did win, but it's pretty easy to stipulate that his boring persona hurt him, of course it's hard to see any other candidate as the nominee that year since he was VP and all. Obama managed to overcome a lot of the party establishment by actually winning some of them over. This year, Bernie was the Dean candidate: he probably would have won the general but the party establishment steamrolled him and pressured others to stay out of the race to clear the field. It was Hillary Clinton's turn. She was a bad candidate in 2008 and was again this year.
Now, this isn't her fault and it really is frustrating for me to dump on her in the wake of Donald. She is competent and would have made an excellent president, and the negative perception that people have of her is largely due to decades of asinine media coverage of non-scandals. Even if there wasn't that, however, she is just the consummate insider, and a small but significant segment of this country just fucking hates politicians that seem like politicians. (I don't particularly like her but very specifically for her too-militaristic foreign policy stance and friendliness with bankers.)