I would add to the analysis.
“Kerry voters were motivated more by negative feelings for Bush…" Bush spoke about issues in moral terms – good versus evil, right and wrong – a repulsive viewpoint for the Left. To the Left, guns, racism, poverty, and colonialism cause crime, not bad individual behavior and bad values.
“Romney, like Kerry, depended on voters' distaste for the incumbent…” The Romney campaign ran as Mr. Fixit. He may have been more successful had he highlighted, not hid from the ideological differences. E.g. Do you, Americans, want to be ruled by centralized force and coercion of the Left or by more cooperative, compromising, and localized self government as envisioned by the founders?