RogueLeader said:
Pre-transformation Palpatine looks more like Ian McDiarmid with white contacts, to me, instead of looking like the Emperor. I don’t know if that makes sense, but there seems to be very little make-up on him that we associate with the Emperor, beyond making him extremely pale.
I believe the intention was to make it like Palpatine’s spirit was possessing a fresh, un-deformed, new corpse body. Once he is ‘restored’ he resembles the true Sith Palpatine appearance.