My hot take is that dialogue was necessary for this scene, just not that dialogue.

Like we know Vader is switching back to Anakin in that moment and we know Anakin is emotional as fuck and has no issues vocalizing those emotions. This was a super emotional moment for him and he knew he was sacrificing himself, so I think the silence undersells that scene. The “nooooo” was just a lazy fix to that problem though.

I wish they called back to the scene where Anakin helped Palp kill Mace Windu and then fell to his knees saying “What have I done”. That’s the moment he realized he fucked his life up, thats the moment he realized he needed to fall in line to Palp for a good shot at life, and that’s the scene he became Darth Vader.

Imagine him mumbling “what have i done” as he’s watching Luke get zapped, then screaming “what have YOU done” as he picks up Palpatine and throws him over the ledge.

Like that dialogue would vocalize every emotion Vader has in that moment. The “what have i done” would show us that he’s switching back to Anakin in that moment and is horrified by the fact that he was willing to let his son die for Palpatine. The “what have YOU done” shows us that Anakin is no longer blaming himself for the way his life turned out, but is blaming the person who manipulated him, destroyed his relationships, and ruined his life. That would’ve done it for me.