Doctor Who is essentially a show about 1 character: the Doctor. And they fundamentally changed the character twice: first when they started the new series in 2005, and second with the female Doctor in series 11 (and not just because she's a girl).
What NuWho got wrong about the Doctor in 2005:The Doctor is fundamentally not an action-hero type, he's a weird alien scientist largely driven by his curiosity, who only saves the day because he himself gets caught up in some situation needs to get out of it (Think about Hartnell in The Daleks - he gets himself in trouble because of his desire to explore the Dalek city), or people ask him for help (as it was with Pertwee and unit). The Doctor isn't some superhero type, all about 'fighting the good fight' and good vs. evil - this is why Capaldi's speech at the end of Twice Upon a Turd makes no fucking sense whatsoever.
The Doctor is also not your traditional ass-kicking good guy, he uses his mind: cunning, trickery, and also his technical skill to defeat his enemies. He studied on Galifrey (the most technologically advanced civilization in the Doctor Who universe), and this is what gives him an advantage over his enemies. Yet, he is also not a strict pacifist, he doesn't like violence, but he will fight his enemies if he thinks it's necessary. Paradoxically, NuWho got both these aspects of the character wrong.
And above all the Doctor does not fucking fuck, he had a granddaughter, so you have to assume that he did at some time. (Maybe Time Lords only reproduce during their 1st regeneration - but my point is that I don't want to fucking know information like that - because that shit is not what the fucking show is fucking about!)
And just look at the 9th Doctor's costume, I think there was a comment on here that he looked more like Angel than the Doctor, which he does. Angel is great, but he isn't the Doctor. Say what you want about Colin's costume, but I can imagine the Doctor (the real Doctor) wearing it in a way I can't see him wearing the 9th Doctor's costume.
What Nu-NuWho got wrong about the Doctor in series 11:First, there's the whole female Doctor thing. Well, there already was Romana II, who was basically a female version of the Doctor. A Doctor Who-like show with a leading character like Romana II would be great. But the Doctor changing into a woman makes no fucking sense whatsoever.
Even if you could get past that, this new version of the Doctor comes off as neither the wise eccentric old scientist of the old series, or the cool exciting action hero of the new series. Chibs did exactly the same thing to NuWho fans regarding the character of the Doctor that RTD did to old Who fans. The character of the 13th Doctor just falls flat. Jodie's Doctor appeals to practically nobody, except for the maybe two or three people that like to hang out here:
http://wokedoctorwho.com ...
Shit, I wrote a lot. TLDR, RTD fucked up the character of the Doctor and turned him from an eccentric wise old alien scientist into a boring traditional action hero type, this put off classic Who fans. Chibs fucked up that version of the Doctor and just made him/her boring, this put off fans of the new show.