The difference between Hayden/Shaw swap and the Revill/McDiamid swap is that Shaw represents the father that Luke can relate to (the late middle aged man he saw under Vader's mask but restored to a human being) the creepy little child murdering wife abusing scumbag Manikin Skywalker is someone Luke has never seen and could never relate to, especially with that creepy smirk on his face.

The OUT ESB Palpatine looks and sounds nothing like the Palpatine in any of the other films (the DVD one doesn't look right either) so I fully support people like Ady removing the Revill Palpatine but making him more like the one in ROTJ than a Halloween cake that caught fire and was put out with a spade.