that's because those releases were limited runs. If it becomes more common, you could buy them at a cheaper price (I don't think that ABFMV USB retailed for much or any more than the CD). And you can package it with a CD booklet or whatever, and the drive looks cooler than a disc. You can put a USB input into any stereo, so that's not a problem. Just saying this is a viable next gen format, not that it will necessarily happen.
The Amazon listing says $98. And maybe I'm wrong, maybe the USB drives will sell at a reasonable price, but I don't think they're practical or will sell as a mediator between electronic and physical formats. I don't think a USB brings anything a CD doesn't do well enough except for portability (in which case, most music fans have iPods or something of the kind, which can be used to extract music as well).
I would think it would make more sense for a signed band, or one with a distribution deal. Where a label covers it, because if you're buying those things for pressing an album, it'd be wholesale prices, not only that, you could effectively cut most of the workforce necessary to press CD's for a release.
Well again, I don't see why anyone would choose a flash drive over a CD. This is really turning into a matter of preference now. I could never understand why there would be a market for USB over CDs. If there is, well, I stand corrected and I'd really like to know what the appeal is.