Re: New Star Wars animated show "Rebels" coming fall 2014
"Explaining" why Vader is "less agile" than Grievous is the sort of thing I'm not interested in seeing in Rebels, or anywhere else, for that matter.
There are in-universe reasons why Vader's cyborg body and armor don't allow him to be as agile nor physically powerful as Grievous was, and I'm fine with not knowing them. At least one of the novels indicated that the Sith life-support armor he wore for the rest of his life had its limitations and that the cybernetic body parts attached to Anakin's mangled and near-dead body left something to be desired, so that's all that's really needed to know. If Lucas didn't find a pressing need in any of the OT films to describe Vader in such minute detail I don't see why anybody needs to now.
Human instinct is pretty strong. You can't expect us to change overnight.
- Jonathan Archer, 2151