Wasn't there some point made somewhere about mainstream consumers not noticing the difference between texture filtered/perspective corrected 3d and non-such? I agree with that ideology. If no one's going to notice (except the hardcore gamers and early adopters), why invest the extra money (which has obvious drawbacks, such as battery life and system cost)?
Ok, so it'll look a little better. But that doesn't add anything to the game. Most DS games probably won't need it: Metroid Prime Hunters looks just fine. It's not like any of these games have glaring texture warps like MGS or VS had on PS1. And if they do, mainstream consumers will assume it's natural to the way the system works and not consider it a technical problem; i.e. they'll think it might look weird, but it's just something you deal wit much like you deal with ingame character models not looking 100% realistic.
As hardcore gamers ('hobbyists'), I think it's part of our responsibility to zoom out a bit and look at things from a realistic point of view, like the hardware manufacturer (in this case Nintendo) probably has done.
What's to benefit, really, from filtering/correction? I say: so little, it's negligeable. Costs outweigh benefits.