So...you consider it insane to think that a company would increase its pricing in light of a high demand on its product
No, it's insane to think they'd do it in one country and lie about the reason. If it was worldwide or just done in the manner of normal product based price rises (i.e. silently) then it would make some sense (but not too much because you don't fiddle with prices like that after launch, you spend weeks calculating price points, you don't change them on a whim).
By the time they're actually giving the reason they're probably quite embarrassed about it, and it's a highly plausible mistake. If I ask you to calculate pricing for the US, Australia, China, Japan and god knows where else, with your lack of knowledge of the markets in those countries, it seems fairly logical you could make a mistake and if I checked I wouldn't immediately notice it should be 295,000 Yen rather than 275,000 Yen. How would I catch that without recalculating everything - it's in the right ballpark, I probably don't know the current exchange rate, I wouldn't at a glance suspect anything was wrong.
If the price rise is implemented worldwide then will it still be insane to think they are cashing in on high demand as opposed to it being "just a page of number somebody has misread or mistyped or added up wrong"?
No, but it isn't being as yet. It's being implemented in one country and called a mistake, a country with a not particularly large market too. Given that, I'm inclined not to see a conspiracy everywhere and assume it's actually *shock horror* a mistake.
If they were raising the price due to limited supply and massive demand why not just say so? It's £200? Nobody who's prepared to buy a largely untested £2200 camera on pre-order is actually going to change their mind for the sake of £200 when the competition is still £2900.
I'm also amazed (though only slightly, it's the Nikon community after all) by the fuss, it's £200, 10%, of a £2000+ camera. If you're actually fretting over being able to afford that extra 10% then you probably shouldn't be buying a £2000 camera. Otherwise, it's an investment which will last 3-4 years at a minimum and still be worth half it's purchase price then. Which makes that £200 roughly £33 a year at worst in those terms, you might survive...