I feel like revealing Vader as Vader at the end of ROTS was a mistake. They should have gone with a more proto-Vader look. Doing it that way, they could even have salvaged the father reveal in some way (Anakin is sent by the Jedi Order to kill the Emperor and his ‘new apprentice’ and instead falls into a trap laid by the Emperor to make Anakin his new apprentice and we fade to black and later in the film Obi-Wan is dispatched to rescue Anakin, but by then Vader is there and tells him he killed him).

I like to think that Vader is being promoted throughout the OT, since in the beginning he’s definitely subservient to Tarkin to whom Vader is a novelty tool to wield, then by Empire, Vader has been given the largest Star Destroyer in the fleet to hunt down the Rebels and Skywalker personally with guidance from the Emperor himself, and in Jedi he’s the Emperor’s right hand man. And his suit’s level of polish (both literally and in terms of design) reflects (pun!) that.