Geez, I thought this was kind of neat, and then you guys go all wet-blanket on the idea.
Regarding the idea that it's too soon to upgrade, Nintendo has done a good job of continuing to support the previous revision of portable hardware for a few years into the life of its successor. Nothing's really forcing you to upgrade Week 1, and in the case of DSi, holding off turned out for the better.
As far as it being a needless revision goes, the business standpoint is to try to head off Apple at the pass. But the idea that new things shouldn't appear until the technical need arrives is silly. Not many could think of a viable use for two screens when the original DS was first announced, either. And if some wunderkind dev already has a notebook loaded with ideas for the new deck, why should he have to wait until we become bored with what we have?
On the other hand, I will say the way Nintendo has screwed over DSi adopters here is pretty raw. There's only been on DSi-exclusive card even announced so far, and too much of DSiWare to this point has been nothing but clocks, calendars, and chopped-up ports. If the 3DS gets solid support from Nintendo at the start, the DSi will officially have been Nintendo's most useless hardware ever. And how smart is it for Nintendo to announce this before even putting the DSi XL out in the West?
There's plenty that doesn't make sense about how they've handled the successors to the DS, and I'm admittedly usually pretty cynical about games myself, but I'm intrigued enough by the possibilities I can conjure up here (Ace Scientific Investigations in 3D! Virtual Boy games without the horrible pain!) to not just keep my optimism alive, but well-fed.