Huh… well that is annoying. They went out of their way to sell toys (its not even integrated into the story like ewoks, just “there” like the PT).
Anyway I kind of liked the red arm, gave 3PO more depth. But either way (gold in TFA, red in TLJ) I would of preferred.
That’s really the thing for me. I wouldn’t have minded if they just never even addressed it in story. Like, oh this is just a casualty of war that happened at some point in the last 30 years, like his silver leg in SW. But they go out of their way to draw attention to it “you probably don’t recognize me because of the red arm”, only to have it rendered completely pointless by him ending the film with his regular gold arm. If his arm stayed red for the foreseeable future and it was never really acknowledged or made a big deal of, that would have been fine and added to the realism of the universe.
It’s just easier to make it gold in his few scenes of TFA than to make it red in every film going forward from that point.