If you're downloading things from their website anyway, they could include a driver for whatever FS they wanted. They could build on top of FUSE so you wouldn't even need admin rights, probably.
Why not? Packaged as an executable, double click to run? It's not that hard. All those iPod users managed to "install a new filesystem driver" just fine.
Not as convenient as the "just works" FAT on USB, perhaps, but hardly an insurmountable problem. I'm surprised they're not bundling some kind of management program already - asking users to manually arrange files on USB sticks seems a bit fiddly.