I could easily be wrong but I could also almost swear that Walken just being Walken is a more recent trend. It's been too long since I've seen The Dead Zone or Brainstorm to really try to substantiate my claim, but I remember him being at least somewhat different as Max Zorin in A View To A Kill, whatever portraying a KGB test tube superbaby in a James Bond film is worth. Regardless, I like both Jackson and Walken as Jackson and Walken, so I'm fine with what they do.
I read an interview with Walken years ago, where he said that he had great job security because "whenever they need someone to play a Christopher Walken role, they call me." So he knows the score.