Because he makes everything so ugly on its face,
I agree. It's a complete lack of 'finesse'. (Or, at least, a visible lack. In the higher-dimensions of the game of chess, perhaps there's some finesse that eludes me, that's how good it is.)
Where the archetypal Frank Underwood (or, as original, Francis Urquhart) would play dirty behind the scenes to look good in public, and even Jed Bartlet would pull strings behind the scenes[1], Trump taps into a stream where he makes no obvious effort rather than do it apparently effortlessly. Which probably endears him to a particular subset of cynics, as well as an allied set of the subcritical. (Then add to that the opportunistic tailcoat-riders who can move in on the territory.)
My own/others' cynicism/subcriticality/opportunism
[delete as inapplicable] isn't compatible, but perhaps I'd be(/I have been) sucked into an opposingly polarised bull-in-a-Jynah-shop approach.
[1] Or let them be pulled. c.f. when he 'accidentally' made a comment 'off air, but on camera'.
ETA:
No, not the smallest part of an idea, but any idea that reproduces "on its own" by transfer between minds, as an analogue to genes.
Would the 'smallest part of an idea' be considered a m(emory-c)odon? Or a m(emory-b)ase?
(Cue frantic scramble to shoehorn something into "moron". Or, indeed, just "base".)