you can't blame nintendo for exhibiting the confidence it does. first of all, they've earned the right to talk--when your system has been the top seller for over a year (with no signs of slowing down), that's something to brag about. second of all, what you need to understand is that in the business world, sellers must be confident in order to build the confidence the consumers have in their name and quality. if the nintendo suits were to come on television and say something like, "we're doing pretty well right now, and hopefully we can keep it up. we've got games that we think will please our customers, so just hang in there. we're kinda sure we've got the competition beat.", then they'll lose the confidence in their customers. it's all business strategy--act like you're on top, and your customers will believe you're on top.
music artists do it all the time. look at the 50 cent/kanye west battle.