"Prejudiced", "bigoted", "narrow-minded" are words that are spewed out about others and their opinions far too easy. It's disappointing to see the Twitter-like "lynch them now for expressing a different opinion" reactionaries on TV Forum.
Let me offer an alternative perspective as one who is not happy that the Doctor is now a woman.
I am a big sci-fi fan - a big fan of sci-fi characters. Some of my favourite characters of all time have been women, for example...
• Capt Kathryn Janeway, Seven of Nine, and B'elana from Star Trek Voyager
• Laura Roslin (president) and Starbuck (fighter pilot)* on Battlestar Galactica
• WPC Annie Cartwright (Life on Mars)
...and of course, not forgetting...
• Rose Tyler, Clara Oswald, Ace, and Bill Potts, the Doctor's companions.
• Gwen Cooper and Naoko Mori from Torchwood
Part of their magic was the fact they were women. Would a male character as President of the Colonies be better than Laura Roslin? No. Part of all our identities is that we are male, female, or somewhere in between - it's part of what makes us who we are, whether we're gay, straight, black, white, religious, non-religious, etc.
I argue that, although there is no reason why the Doctor should not be a woman from the perspective of what is possible in the Whoniverse, he has always been a male and that has always been a vital part of his identity. I feel that this is messing with the story too much.
It's like Queen. My musical hero is Freddie Mercury. I wish I'd seen them in concert. "Queen" have recently toured with the very talented Adam Lambert and earlier Paul Rodgers. But because a fundamental part of their identity is no longer there (Freddie + John Deacon), they're no longer Queen. They're a different entity.
This make me a purist. This may make me a snowflake. It may make me many things, but it's not a sign of sexism, bigotry, etc, to want the gender of the Doctor to remain male.
* Yes, I know Starbuck was originally a male on the 1970s Battlestar Galactica but the re-boot was almost a completely different series from the original
OFCOM's queen bitch