Don’t we literally see his face melting in the original cut? That doesn’t imply “Palpatine’s real look” to me.
Like I said, not very well implied in the film. He was purposely manipulating the visuals to look that way. Either that, or what you see “melting” is his fake face. Otherwise, why don’t other characters turn into a mini-Palpatine when they are electrocuted?
I believe the novelization that was released around the same time of the movie talks about it. Palpatine thinks to himself, and I’m paraphrasing here, that the face of Sidious will prove helpful in convincing the galaxy to stay by his side, and that the face of Palpatine has served its purpose.
So Hal’s change to ROTS just makes that idea more clear.