Instead of the always optimistic and chipper Doctor, we suddenly had someone who didn’t seem to care for his companions, let alone the rest of humanity. That’s the fundamental message of all kids’ stories: as dark as it gets, the dawn will come.
Moffat recognized that he had taken things a bit too far with this version of the Doctor, and in the follow-up season with Capaldi he tried to mellow the new Doctor out a bit. No show has so many endings and so many beginnings as Doctor Who.”, so maybe he could do it again. Another idea might be to bring back David Tennant himself as the Doctor.
The Doctor's quirky personality and alien behavior are part of his toolkit, but for all his outlandishness he takes his responsibility to protect the innocent extremely seriously.
While there’s no denying that both Peter Capaldi and Matt Smith have been excellent, it’s also true that the show has not had the energy, or the ratings, it enjoyed under Tennant and Davies.
It's been more than six years since they were last seen together in the Whoniverse so for fans of Doctor Who, the reunion of David Tennant and Catherine Tate is a pretty big deal.