My irritant with the scene is that the Emperor SOUNDS nothing like does in ROTJ. In Jedi he speaks at a faster rhythm with more inflections in his voice. This goes the same for Ian McDiarmid's prequel performances as Sidious. They sound completely different. There are very few brief moments where he's approaching that, but after he makes the full reveal in ROTS, he talks about one-quarter speed just to sound more intimidating (which I don't think he pulls off).
The Emperor just seems more devilish to me in Return of the Jedi. He actually comes off as deceitful, manipulative, cunning, and sinister. He personifies evil, and his presence alone is frightening. I could see Anakin being more easily seduce to the Dark Side by the Emperor in ROTJ than the hammy, and often, cringably acted Palpatine we got in the prequels.
-NJM