Given how challenging Doctor Strange must have been from a visual point of view and the aplomb with which Derrickson pulled off the film, he’s surely a natural choice to return.
Moreover, the film was stunning enough to earn an Academy Award nomination, so why fix what isn’t broken?
Furthermore, Cumberbatch himself has expressed a desire to work with the director once again on the sequel.
With that said, perhaps some fans would enjoy seeing another director’s interpretation of the character.