David Leonhardt delved into this issue in Democrats Still Need a Story, asking readers to come up with A Better Slogan. He received 1,200 responses and collected the best ideas: A New Democratic Slogan? Your Choices. And these really do sound like the best ideas as ideas go.
I would argue that all of these "good" ideas are doomed to failure for many of the same reasons that the Candice Bergen character's best idea fell flat in "Starting Over" after her husband divorces her and then takes up with another woman. The performance of the song "Better than Ever" could be played as is at the next Democratic convention (sorry for the darkness):
Democratic strategy fails because it is so difficult for people to understand the thinking of other people who do not reason the way they do. Rational, analytic thinkers often have difficulty understanding the minds of conservative, intuitive people. The Dems believe that they just need a better message to get through so that voters will focus on policy that will benefit them. But many instinctive people vote based on trust and they trust people who think and talk like they do and mistrust people who do not. These conservatives vote for a person, not a policy outcome. Policy is complicated, but deciding if you like a person is simple.
I think back to the political arguments my late mother had 40 years ago with her father who worked as a member of the Teamsters in the trucking industry before he retired in 1967. She would argue that FDR's policies were responsible for his Social Security which he should appreciate. Without Social Security, he would have negligible retirement income. But he was not voting based on policy or the personal impact on him . He knew who he liked and it was not the Democrats. He liked Jimmy Hoffa despite the meagerness of his own Teamsters pension. And despite Hoffa's obvious corruption.
Trump brought a slew of new irrational voters back into the political process - people who had given up on hearing candidates who spoke and thought just like they did. And no one is suppressing the ability of these white voters to cast their votes. Republican strategists want these voters to remain engaged and actively voting.
No, the Democrats will never get through to these people with policy arguments, no matter how clever the messaging.
Democratic strategy needs to focus on fighting voter suppression and inspiring the Democratic base. Maybe a better than ever slogan would be "Vote or Die - It's Up to You". (Late update. Oops, apparently Vote or Die is already taken. You get the idea.)