I was thinking, the other day, that Doctor Who really shouldn't work. I mean, one of the most important rules of science fiction is that explanations must be plausible. That's not to say they have to be possible, but they do have to make sense at the time they crop up and they have to be believable in their context.
Explanations of things in Doctor Who are very, very frequently totally implausible. But maybe DW isn't science fiction, despite the space (and time) travel, the aliens, the ray guns, etc. Maybe what it really is is fantasy with the trappings of science fiction. And yeah, I agree with that. I do think DW is more science fantasy than science fiction. But one of the most important rules of fantasy is that fantasy settings have their own rules, and everything that happens has to adhere to those rules. In other words, fantasy has to be internally consistent. If it isn't, then the viewer/reader gets jarred out of the fiction and becomes aware of it as fiction, and that's to be avoided in an immersive story.
And Doctor Who isn't internally consistent. It contradicts its own rules all the time. And yet it still works. OK, maybe it doesn't work for everyone, but it still works for an awful lot of us. So why the heck am I not bothered by sciencey-sounding explanations that don't make sense and world-building that contradicts itself? Why is it that the DW creators can get away with things that almost no other fiction--written or filmed--can?
I don't really have an answer, but I think it might have something to do with the fact the show is just having too much fun, and we the viewers are having fun right along with it, to the point that logic and consistency and plausibility somehow don't matter anymore and don't pull us out of the glorious fiction. Or maybe it's because we already know there will be no logical consistency, so when inconsistencies show up they're expected and don't pull us out of the experience.