I have a drawer full of working USB portable hard drives ranging from 120gb to 500gb, most in eSATA enclosures that also have USB2.0 that work just fine.
and most of the time I run them as eSATA drives because it's faster
I can't imagine being so lazy as to be willing to suffer through
the slower data throughput of WiFi to a USB stick
Though I can see it being useful for additional storage without wires on a
tablet that lacks a USB port or microSD slot