The problem with 'character matters' is that you aren't voting for a person, you're voting for a party and you're voting for policies.
That's simply not true. Every day the president has to make decisions, talk to foreign leaders, respond to unforeseen events, and do plenty of other human things that only a human can do. A lot depends on their personality, judgment, temperament, and so on. The last three years provide excellent evidence of this. If Trump is no more than a list of a policies, his administration should have been no different to his predecessors. Instead, it's been a chaotic, dysfunctional mess, which we can attribute to Trump's laziness, erratic personality, and general incompetence.
People voting for character is why we got Trump. There are some lifelong republicans who voted for the party no matter who was in charge of it, but there was so many more who rabidly supported Trump because of how he acted, because he didn't act like a typical politician, a cult of personality is what got him into power. Voting for character is also where you get the diehard Bernie fans who don't vote democrat or vote Trump out of spite for their person not making the ticket. They become so obsessed with character and the person that they don't realize that they're meant to be voting for policy. It happened in 2016 too.
Maybe I wasn't entirely clear, but I'm using the word
character to mean the moral and ethical qualities of a person. It's not synonymous with personal appeal. If character had been a major concern in 2016, Trump would never have been elected, because most people could see that he was a foul person. But just enough people held their noses and voted for him, presumably telling themselves that they could separate the personal from the political, that they were electing Trump simply to do a job, that he could be a good president without necessarily being a good person. They were wrong.