It's a long established fact that an appeal to emotion as opposed to rational argument or character, is a far stronger form of persuasion. I think a lot of people overlooked this in this election.

Sure, people will justify their support either through reasoning or judgement of character - "He's a racist bigot", "She's part of the establishment", his/her policy is better etc. but what it comes down to is the emotional appeal of the arguments.

I think Donald Trump was more successful at rallying people around his promise to "make America great again" whilst Hillary failed to rally people around the idea of "Stronger together". I think her campaign became preoccupied with attacking the character of Donald Trump, seeing this as his weakness, as opposed to founding it on a strong appeal to emotion. I would argue the Sanders campaign was much stronger in this regard.