Interesting innovation, but I would be more interested in having drive-less bus-powered enclosures to put my own 3.5in hard drives in. I'm not really fond of having to buy a unnecessary Seagate HDD with it.
For me the power supply thing is mostly a non-issue, because I use bare desktop drives inside USB/eSATA docking stations and tray-less mobile racks. Docking stations stay on the desk and are powered on their own while mobile racks are simply powered by the PC PSU.
Of course, doing that one has to be cautious because of ESD (sadly SeaShield is long gone), but that is not much different from handling bare optical discs, were you carefully have to avoid touching or scratching them, too.
OTOH USB enclosures don't solve the most immediate danger while handling 3.5in HDDs: mechanical damage. The latter is the best reason to avoid them and buy robust 2.5in hard drives instead. Also those are bus-powered for a decade already.