I think it was appropriate in this case, as the person boasted that he was expert enough to identify incorrect sentence structure (and was completely wrong).
My take on it, is that the Jedi (Vader included) were well-educated polymaths who were more likely to use refined, grammatically correct language than colloquialisms.

You're telling someone whose first language isn't English that they should have said well instead of good, wow. Already pretty pathetic that you're a Star Wars dork, didn't think there was much worse. You proved me wrong. congratulations

It's actually perfectly correct English, though not a very common phrase. Using good as an adverb, however, is not.
Requiescat in pace, Krystle Papile. I'll always miss you. Justice was finally served.

"Blasted Biggs, where are you?"
I thought it was "Blast it Biggs, where are you?"
"blast it" is colloquial for "damn you"
"He's dusted, busted and disgusted, but he's ok"

It simply sounds more regal, refined and sinister than, "You know it's true". Star Wars is known for these kinds of phrases, like, "What in blazes is he doing there?" or "Blasted Biggs, where are you?". No one talks like that, it's part of Star Wars' pulpy roots.
"Aren't you a little strong for a lady? I'm calling wang"