I loved 13 and 15 & I have seen a pattern with writers not getting the Doctor right particularly with those 2. But I have a theory on what happened.
So, Let’s talk about the elephant in the room.
Classic whovians were largely white males until the reboot when females… mostly white, evened the demographics. Until 13, we only knew the Doctor as being a white man. The writers never took a golden opportunity to address the issues the Doctor would suddenly due to no fault of their own, find themselves in. Not as a main issue, even use humor. Lets say someone idiot slaps her on the ass and winks as he walks by her and Yaz. Lets say 13 stops in shock and asks Yaz why the hell did he do that? Yaz could laugh and respond with something like. “I guess you never had that happen when you were a white guy. It’s worse if you are brown or black”
Then I would have liked to hear from her, “Well that nonsense is fixing to stop!” But then perhaps 13 mentions something about Gallifrey used to have 5 genders and 15 races but the only ones who were placed in high esteem were the TimeLords.. one of the reasons she first left. The companion is doing their job, character development happens, and an important social topic is brought to the fore front.
Same with 15 but have the Doctor dealing with Racism from his POV for the 1st time.
IMHO, too much hype was spun around them being the first woman and black man in the role, to maybe bring in more fans for ratings. The Doctor is the Doctor. An alien from Gallifrey. Last of the TimeLords. I also believe that when white males are writing about a woman or a black, brown, person etc… they are guessing at best how to write that character from a POV they have little to no personal experience with. (Meaning a woman or black) Perhaps The showrunners were so obsessed with ratings to make sure Dr Who “looked” modern that they missed out on why the fans have stuck with the Doctor for over 60 years.
For me, it’s the stories and The Doctor of course, but the companions are not there as a prop or a tool to for ratings. The companions are integral to the show as well. I also believe using regeneration gimmicks for ratings shows the lack of confidence the showrunner has in their audience.
Am I angry with RTD? No. I think he has gotten sloppy and loves gimmicks.
But more so, he is out of touch.
As a fan, I really enjoyed 13 as the Doctor and Jodie did great with what she had. But I always felt something was missing. When I saw 15 crying the first time, I was thinking The Doctor doesnt cry. Not that it bothered me BUT, perhaps maybe the white writers didnt want him looking like a stereotypical angry black man. 
Despite some awkward and lame writing, Gatwa did a fabulous job. Again, I knew something was missing.
The following is a fabulous article from a black Dr Who fan with advice on the perils of white Dr Who writers who have tried and failed to deliver time and time again
https://jakewiafe.medium.com/black-doctor-who-white-writer-my-problem-with-dot-bubble-38aa33ec8137
Personally, I am always ready for a new Dr when the previous has regenerated. However, This scenario reminds me of when I saw the movie Barbie when she got to the so called Real World and to her shock and horror in discovering that the ceo and shareholders of Mattel were old white men, She gasped, “What? No women?”
Gatwa was Black Ken in that wasnt he?
I get this sinking feeling the writing gets crappy or lazy because the showrunners would rather have action, glitz, pomp, & cgi to push ratings. Quality takes more effort. I dont mean to sound cynical, I am still reeling a bit from the Finale😜 but this seemed worth a mention.
I am anxious to see what some of you guys think about all this.
