DW is not all about change.
DW came up with a neat idea that allowed it to get round the lead actor changing. It has remained the same basic formula however. The TARDIS as the same police box for instance, its still the same villains (if its all about change and renewal why not ditch the Daleks, the Cybermen, the Master, the Sontarans, UNIT, the Brigadier?)
DW has a formula and a template that it has to stick too or else it wouldn't exist. Its like Batman. Batman has changed drastically over the years. He's been a gritty down to earth crime fighter like in the Nolan movies, a sci fi hero like in the DCAU, a comedy character like in the Adam West series, and a gothic, horror movie hero like in the Burton films.
Arguably he changed MORE than the Doctor. However there was always a template that every version of Batman followed, living in Gotham, being motivated by the murder of his parents, not having powers, having a utility belt, a particular set of villains, and supporting characters, Commisioner Gordon, the Joker etc.
If you don't stay within that template then you are not doing Batman, same applies with DW.
Now in regards to a female Doctor I have never liked the concept. The character of the Doctor, though he changes also has a template that he stays within. His gender is obviously a part of that by default. He's been written and acted as a man automatically for over 50 years. Men and women are different. They are equal of course, but there are differences, and turning the Doctor into a woman would seem out of place for me.
Also its a difficult thing to pull off in the show. Are we going to rewrite every time lord to be genderless? That's stupid. Now Susan can be Brian Blessed for instance. Or are we going to rewrite the Doctor to want to change like a transexual. I have nothing against transexuals, but its stupid to suddenly rewrite him into being that after 50 years (10000 in his time.) Why'd he never change into a woman before?
Having said all of that I have grown to despise a female Doctor because the only reason it happened was the SJWs bullied and slandered Steven Moffat as a sexist, a racist, a homophobe, an abelist etc, until he caved in to them, and now they are attacking the fans as sexists and racists.
And in what way was Missy not a failure? You seriously think that was a good version of the Master? I'm sorry but no I don't believe you.
She was like a parody of the Master. In fact she was like a sexist joke told down the pub. If the Master became a woman he would want to shag the Doctor, and he'd have to be all weepy and sensitive, and he'd no longer want to conquer the universe, just spend time with his "boyfriend". Oh and he'd also have to be a rabid feminist too.
See here.
http://tardis.wikia.com/wiki/Girl_Power!_(short_story)
http://tardis.wikia.com/wiki/Dismemb..._(short_story)
Seriously? You think that's a great development for the character? Seeing him hijacked for some petty political agenda and turned from a manipulative criminal mastermind like in the Deadly Assassin to a hormonal, love struck, feminist, handing the Doctor an army of Cybermen, getting jealous of Clara and Osgood and launching a campaign against rats!
And if you want evidence for SJWs taking over DW please take some time and read this article I wrote that provides citations from Moffat as well as his critics that show how DW was taken over.
https://t.co/CmgNhqs6W1