Yeah, I thought of that, but I don't think that's the case, because there are plenty of cheap semi-hollow ES335 type guitars, which are harder to produce than a chambered solid guitar. And even in the higher end market, you don't see that many. The thinline Tele is really the only major one around.
Maybe the market is driven more by looks than sound? Or it could be because guitarists are so conservative about body styled.
-Sven
I've got a '99 Gibson Les Paul Double Cutaway and it has a chambered body. I am pretty sure that all of the DC models have chambered bodies. I love it because it sounds great, is a lot lighter than a regular Les Paul body and the DC shape gives you more fret access.