Things change. The end of the Moffat-era as a showrunner and the change in the main character’s role could be sensitive for the fans, but after this season (the lowest ever in the ratings) the BBC was in for something more than a few replacements.
Steven Moffat did a great job, with some minor glitch here and there, until Peter Capaldi came in the show. I’m sure it’s coincidence, but it still troubles me to see that one of the best available actors has been set up with the weakest streak of episodes in the last few years. A new showrunner was needed and Chris Chibnall is a very strong choice.