I must say, I'm actually really disappointed with a lot of the reactions to the announcement of a female Doctor Who, but mainly by those who have posted to messageboards and comments in favour. The reason I'm disappointed is, with only a relatively few exceptions, most of the anti brigade have shown their dislike for the change, but not in a way that attacks anyone (except perhaps unnamed BBC producers, Moffat or Chibnall), and whatever their reasons, some stated, some not, have been met with a lot of personal abuse and accusations of mysogeny. That I've seen very few have had a problem with Jodie, just with what is a significant change to a character that's been portrayed for fifty odd years. Whether you're pro or anti, everyone is entitled to their opinion, and attacking someone for having a view is unnecessary, distracting and just plain unpleasant. The gloating 'aww poor men/ broflakes' etc has nothing to do with the arguments for and against casting, and just makes those posters look petty and nasty. But as for my view on the casting decision...
Aside from the various 'its a male character', 'non violent male role model' arguments, which I've discussed with various people, and which have a reason behind them whether you agree with the view or not, my main concern is about the ability for the show to continue in its current structure without vastly improved writing. Historically, the show has worked (in terms of ratings and broad audience appeal) best with a dynamic between Doctor and companion which is male/ female split. There have been a few short lived exceptions, but most of these were in 'classic' era, when most stories had a runtime of almost two hours, giving enough space to develop and sustain multiple assistants, something the current format doesn't allow, meaning Nardole/ Rory for example being bit parts to a 'main assistant' rather than being rounded and developed in their own right.
I'm talking narratively and in terms of demographics here, but for a female doctor as opposed to a male one, to maintain the proven formula, you'd want a main male assistant. This isn't a problem (Jamie was one of the best, though he needed Victoria or Zoe to really work well) but how would this realistically be characterised? Part of the success of the relaunch was Russell T and Moffat's explicitly stated intention that the companion is the lead character, for audience identification purposes. While I personally think this got too much with Clara, it worked well with Rose, River, Bill, Donna etc Pairing a new female version of the Doctor with an independent male companion (which given the current casting trends would be a young man who fancies the Doctor, probably non caucasian to make up for the fact we have yet another white tentpole casting) will likely cause complaints from those who wanted a female in the role that it undermines the 'strong woman', even though it would be a mirror of the previous pairings. Or you cast a weaker male, risking losing the other side of the demographic in the audience. And probably the section of fandom brought in by the equally cynical appointment of Tennant/Smith to appeal to the casual viewer who wants an attractive looking male lead. Or gawd save us Kris Marshall as the companion.
I'm not saying it can't work, but its a hell of a risk for a ratings dependent show, as sticking with the 50 minute episodes that dynamic between Doctor and Companion is going to be crucial. If they were brave enough they'd have a companionless Doctor for a while, which might work very well with Jodie, who is a great actress, but I doubt they will. I suspect they'll fall back on the 'safer' route of bringing back some 'greatest hits' (Vastra/ another weak Dalek story/ possibly Jack) with a new male and female duo or I'm guessing an alien companion who happens to look male (and photogenic). In other words, only half committing to change (a bit like they did with the first series for Capaldi as an older incarnation). On the bright side, having taken this risk we're pretty much guaranteed a few more years, as even if ratings tank after the initial spike of the new Doctor, the BBC wouldn't want to look like it made a mistake on such an emotive issue.
So my, at least, issues with the new casting are about the ability to deliver a show which is still recognisably Doctor Who, in an effective way, in the current format, with a companion (essentially the lead) that will appeal to everyone. I hope I'm wrong and am quite willing to be proved so but I think its a needless risk when there are so many well formed female characters in Who quite able to carry their own series and act as the female role model the comments sections keep on going on about, without gambling on changes to an existing franchise, and like it or not, it IS a gamble. Whether you agree with me or not, and if you have a different opinion, fine, if you're tempted to comment anywhere, I'd ask you try and focus on the issues of the character and the practicalities of changes to a commercial product and its demographics, and not just insult anyone who doesn't agree with you. Maybe you have a valid solution or different interpretation of how it might work, so fine, post about that instead. I hope you're right. And I'll quite happily post I'm wrong next year if I'm wrong, in fact I'd be delighted to.