What this should tell you is that Nintendo's overall goal is, and always has been, about making money. Nintendo doesn't care about market share, or raw unit sales numbers, or how many games they have rated highly on Metacritic. They simply want to make money, and they evidently felt that the depreciation of the pound was slashing their profit margins to unaccceptable levels. It's definitely a bit risky though, because of the negative PR effect. (Although to be fair, most of the people who are "outraged" are fans of other consoles, who probably wouldn't be buying Wiis anyway...)
The freefall of the pound is great for me, an American living overseas in London right now. I'm getting almost $1.30 to the pound in official credit transactions; two years ago when I was here, it was $2.20. A lot of companies haven't adjusted their pricing yet either, meaning you can get some stuff way under cost by paying in pounds. It's absolutely TERRIBLE for anyone who actually resides permanently in the UK though, and gets their income in pounds. Sorry folks, I feel your pain.