Not a fan of the SEs or this change, but the usual reason given in favor of it is that Vader’s hiding information from Palpatine. He doesn’t want Palpatine to know that he already knows Luke is his son.
It raises a few more questions, though. Like, why would Palpatine care if Vader already heard about it? Or, why is the movie bringing this up when it’s never really relevant again? Plus, I don’t think that’s actually what Lucas had in mind when making the change.
Yeah, agreed.
But that explanation isn’t so horrible, and while I much prefer the original, it’s good enough for me.
My biggest issue with adjusted the dialogue is that to first time viewers watching the SE edition, Vader’s line of “How is that possible?” is going to stick out immediately as an error or at very least be confusing after what the film sets up until that point. The explanation that many people give the change probably won’t be clear straight away. Not that it’s even very clear if you spend ages thinking about it. 😉
I wouldn’t call SE fans insane, though.
Noted, OP edited.