I for one, would much rather have higher battery numbers than a backlit keyboard. I'm frequently away from power sources for long periods of time and especially because the Air's battery is not user-replaceable, a long lasting battery is very important to me. It went all day at work yesterday without it being plugged in at all, and I just have the 11". I used it off and on for a variety of normal tasks, and it still had juice by the time I got home. Brownie point for Apple!
But again, that's just me. I know what my needs are and I bought accordingly. I suspect that the best way to vote on this issue is with your dollars. If a consumer doesn't like what the Air has to offer, then they shouldn't give Apple their money. I would think that for the next incarnation of the Air, they will weigh how much of an issue the absence of the backlighting was, mostly by how many units were sold and how much money they made on them. I would guess that even without the backlit keyboard, these units are flying out the door like hotcakes because of features they do have that other Apple models don't. Who knows that but in the next version we might see a lot of these "extras" remain incorporated or come back just because they've now figured out how to make ALL the pieces work at a reasonable cost with fewer tradeoffs: size, weight, battery life, full OS, battery indicator, card reader, backlighting, sleep light, screen gloss choices, or whatever feature it is that a particular consumer can't live without.
Personally, I happen to really miss the Expresscard slot that is on my MBP... but... I do realize that it's pretty unlikely they are going to put one on a computer this tiny.
I've also learned that Apple support threads are 98% filled with people who are complaining about problems of some kind.... it is a truth that feedback is mostly heard when something is going wrong, and almost never when it's going right. I'd guess that for every one person in the Apple support community, unhappy about the absence of backlighting, there's a hundred who are either happy it's gone, find it nice but not essential (I'm in this group) or just don't care one way or the other about it. I'm not saying at all that it's bad to be unhappy about it.... just that the existence of this thread really isn't a great indicator of whether this is truly a widespread problem for most people.