I think this is essentially it. He appeals to the ignorant, the uneducated and the stupid, to racists and sexists (whether consciously so or through ignorance) and the people Michael Moore talked about, the downtrodden who feel ignored and who believe or hope his lies are not lies and that he will do something for them while unable to see that Democrat policies are what would help them.
In some ways, his is a personality cult. For many people, he's a wish fulfillment fantasy, spouting the hatreds and resentments they can't express in a world they consider to be too politically correct even though what they really want is to make America white again. For a lot of people, especially older people, maybe they feel like he's pushing the world back to something they agree with and understand.
In terms of actual policies, maybe W was even worse. But, in terms of what he represents and the sheer hatred he's fanning, Trump is far worse. He's also a short-term gain and a long term disaster for the Republican party. He appeals to a voting block, a generation of voters, that is dying off.
I think it is critical that he loses in 2020 as a way of delivering hard evidence to the Republican party that they need to change. A win would only reaffirm to them that this appeal to the worst racial/ ethnic/ religious bigotry is what will get them votes.