I suspect that you are not target audience!! Not that I am either, I have not watched much of it recently.
I do find it amusing that people object so much to "box ticking" casts but presumably thought it was fine when casts were pretty much exclusively white and middle class - despite the fact that has clearly not been realistic for decades.
Personally I think the pendulum has swing a tad too far and non white or gay/lesbian characters are probably over represented now, but us white chaps can hardly complain having had the upper hand for so long. I expect that it will adjust back and hopefully it will all stop being something that is thought about and we will just naturally have a representation on screen that mirrors society.
Oh and I quite like John Bishop!!
Oh here we go that didn’t take long
what’s your issue with a black actor playing Dr Who 
The thing is that the creators and the BBC are changing white established characters to non-white, female or a more diverse cast and more focused on that than actually writing a good doctor who show. That and these woke people behind BBC are too lazy to make another show like Luther (which was a very good original show) where a non-white, female or diverse actor/actress or show can stand on their own merits. But instead, they want to change everything about an established British show for their left ideology and destroy anything that is the British identity.
BBC care more about ideology than making a good show these days and this new Doctor Who actor proves that for now. That said if he becomes a very very good Doctor Who then they had really good reason to hire this actor. For me, if the main established character's sex or race is changed from the main source but the actor/actress did an amazing job then the creators had a good reason to cast that person.
Does anyone remember when Heath Ledger was announced to be cast as the Joker in the Dark Knight? I remember many Batman fans saying this was a terrible choice as Heath was too young and too pretty to play the joker. Once the film was out everyone took what they said back. So I don't think people care if a main established character's sex or race is changed
if the actor/actress was great. But let me be real this is rarely the case these days. And a great actor can't save a bad script - case in point Doctor Who.
I am just annoyed that these Woke companies are not using diversity to help minorities and put them in high positions but they only care to trick this diversity check box and do this for their ideology regardless if minorities are in bad established shows or not. On top of some times, they pick minorities that aren't qualified for the job and therefore make us look worst.
Side note: I stopped watching in the Peter Capaldi Doctor Who era which I think most old school Doctor Who fans did as well. The woke stuff and bad writing were already in that era and I think BBC put a female/black-gay doctor in the later eras to hide the bad writing.