I always wanted Vader to come back in the books. Back when they were still considered official canon, before the prequels, Lucas basically said Vader is dead he will never be revived for the novels. He kept his word on that. If the new guard ignores that they will really be splitting the fanbase, whats left of it, even further down the middle.
As for the suit, Vader wasn't intimidating because he wore black, he was intimidating because he could kill you with his thoughts, any Moff or other non-Force sensitive person trying to "spook" people by wearing a Vader costume will still have to find a way to kill people with their thoughts or else they won't fall for it.
It could be like the Hand of Thrawn books though where they basically create a fake Thrawn and spook the Alliance into over reacting just because of how cunning the real one was. In that scenario it could work for a short period but eventually people will catch on. Vader was also intimidating because he reigned in a time where people had forgotten the Jedi as he had already begun hunting them down. Any people alive during his reign would have feared him even more because they weren't used to the power of the Jedi. In this series presumably Luke should have at least stated training some new legion of Jedi so people will be more open to the Force by now making a Sith Lord less intimidating.