It's more like "Coherent And Therefore Right".

But if you wanted that, you already have the real world.
I like the absurdity of TES lore, it's what makes you actually think. Going on a model rigidly based on the real world, whenever a question comes up, you just pull out your prior knowledge of reality and totally solve the problem right there. "Cyrodiil went from a tropical jungle to a forest... clearly it's just climate change". Simply connecting one dot to another, and going no further. Now, on the other hand, "So Cyrodiil went from a jungle to a forest because a Hero did it? Ok, that's just totally [censored] weird; why and how did he do it?" I think it's perfectly fine to question it like that, because that's what keeps you going after you connect the first dot to the second. And there are lots of dots around to connect, thank the writers for that.

They didn't have gunpowder in Oblivion, so no, maybe on a pirate ship though.

I'd rather reserve that for the Monomyth, then use it to explain what Marketing has to do with Lore. Which is (and lets be honest about that) the only real reason for the change.

Or, as the recent fan interview makes me believe, the preferences of the silent majority of fans extant within Todd Howard's head.

We really need somebody to do http://xkcd.com/285/ every time Todd is interviewed. It'd save a lot of confusion.