Or using the copper. Plenty of Amiga games played palette tricks despite not using HAM.
Sort of fair but also very specialized.
Not at all! Use of the Copper to punch up visuals was de rigeur on the Amiga - Amiga games are immediately recognizable by their Copper-fueled sky gradients for instance. I actually think that if there's any really good explanation for why you like might find Amiga graphics more pleasing than VGA, the Copper is the thing.
That's the highly special hold-and-modify mode (https://en.wikipedia.org/wiki/Hold-And-Modify). I tried pretty hard to word my comment fairly, remembering the sometimes legendary tenacity of Amiga fans. (Which nowadays includes yours truly.)