One of the main reasons for the Uniparty phenomenon is actually something that should resonate with the left, namely, their desire for a constant stream of foreign wars to enrich defense contractors. McCain was the poster boy for this sort of approach. Trump ironically is too much of a pacifist for the liking of the Uniparty. He supports a strong military but only wants to use them defensively, not in adventures like the Gulf wars and Libya.
There is also the elitist view that only “folks with connections” should rule the peons, if anything an entirely anti-republican (small r) concept. Trump is a genuine Republican in that he understands the foundations of a republic.
We used to think highly of George W Bush but in retrospect, he was only marginally different from his two main opponents in two presidential terms.
Other than Justice Alito, he didn’t accomplish that much.