The truth is, I don't want Nintendo to at this point in time, Pale.
Really, I do want a better screen, a sharp screen with tiny, itsy bitsy pixels. I completely agree with you, that's much much better than the DS screen is at the current size.
But... I don't want it to be a minor DS upgrade, on par with the DS lite, DSi, or DSi LL. Essentially, all I'm trying to say is I don't want to miss out just because I don't want to spend a $180-ish price tag to enter into a little segment of a market I'm basically already in, and if Nintendo did what you wanted at this point in time, it would be all the more reason to need to, as more games would come out utilizing larger pixel dimensions, etc.
So the difference in our opinions is simply that the next DS iteration with a great, sharp screen should be a serious upgrade, or at least offer something more substantial and serious beyond a few retail titles here and there and a library of mostly mediocre download games. If Nintendo offers a genuine successor to it's handheld lineage, then yeah, I'd love it, but that's not the DSi or the DSi LL. These two systems, to me, are the GameBoy Color of the DS world, a needless upgrade that will be completely outperformed and outdated, in a year or two.
But the DSi LL isn't that system, and to try to do that to the screens would just segment and confuse the market, in my opinion.