I always feel really awkward saying that I don't much want a female Doctor either, because people tend to jump on you and accuse you of being sexist or something. But I don't much want a female Doctor. I'm not sure I could really explain why I feel that way, I just do. I think you've probably hit on most of it here, better than I could articulate. Most people think of themselves a particular way and it just seems unbelievable to me that the Doctor would suddenly start thinking of himself as a woman, and want to stay that way for an entire regeneration.

I feel like making the Doctor female would just be a stunt, sort of, like them trying to be bold and forward-thinking and 'hey, look at us, we're so radical, we changed the Doctor's gender'. But then, watching Missy made me half feel like they only did it so the Master could finally kiss the Doctor and not offend the more traditional audience members. And, yeah, to be new and different and spice things up. *shrugs*

IDK if any of that makes sense, like I said, it's mostly just a gut feeling I have that's hard to put into words.