For the most part, it's because on a certain level, I do relate to the Doctor... and I would be extremely uncomfortable with anything coming along that would stand in the way of that. An ethnic change would not make a blind bit of difference...but a gender swap would certainly do that.
I appreciate strong female leads... but I do so for completely different reasons. When I watch a film like
Amelie or a show like
Buffy, or from Doctor Who... the episode
Blink; I like the main characters because I'd like to hang around girls like that.
But when I see a male characters I Iike.... it's usually because I relate to them, I can see something of myself in their character.
So I'm drawn to both concepts for different reasons (and perhaps I should post a list to this effect in another thread). To have one show that has meant so much to me for one reason... suddenly change overnight and not be that any more, would be like having my nuts symbolically cut off. Yes I realise I sound like Londo.
Yes I do realise there's a deep fear of misandry that is somewhat fuelling this but you also have to remember that people are very possessive about the Doctor. they usually latch onto one of his incarnations and say that he was "their Doctor". Tennant even got the chance to say it onscreen to "his" Doctor " 3 minutes and 30 seconds into
this clip from Time Crash... you can tell he said it with genuine conviction.
As for an American Doctor, I probably would be resistant but not as vehemently opposed to a woman Doctor.
But you see if you ask the British... they will say that the Doctor epitomises Britishness/Englishness and it would therefore makelittle sense to cast an American.
However with the right actor,I could probably be convinced... eventually.
Incidentally whilst prepping stuff for the church summer camp I'm doing, I noticed a massive mistake in
Blink.
Watch this clip and pay special attention to 3 minutes 40 seconds in. The camera is mounted too low and you can see all the scaffolding and rigging holding the floor to the TARDIS set, up.