Just want to point out that John Williams stole literally everything from Holst. Listen to Mars: Bringer of War and you can literally see scenes from Star Wars in your mind because it's basically the same thing. In fact, all modern movie composers took great "inspiration" from orchestral pieces of the early 1900's. It's as blatant as when rap artists use "sampling".
On topic: memorability of a piece is mostly down to simplicity. Everyone knows Beethoven's 5th because of the "da da da dunnn", but most don't even know the rest of the piece. Anyone who's even passably familiar with Undertale's music will recognize it if someone hums a short stream of notes; how "good" it is will largely be up to opinion, but it's impossible to deny they're catchy.
The thing is: it's relatively easy to take a simple, chiptune-esque piece and make an orchestration out of it. But doing to reverse is nearly impossible, except for the simple parts of the piece.