I've seen those and I would think they'd be OK for a lightweight bike for street use only.
My concern about a heavy bike or off-road use can be summed up in one word:
Torque.
When I was considering adding a rear spare tire carrier to get my tire out from under the body, I found several that would attach to the receiver. They all looked very slick and I loved the idea of a carrier I could easily remove when it was not needed.
But what kept nagging me was that issue of torque. Specifically, what happens when you are on a bumpy trail and that heavy load is swinging side to side. That hitch was designed to carry a fairly static load, or at the worst, a load that is bouncing up and down. It is absolutely not designed to carry a load that is twisting side to side.
My biggest fear (and the thing that kept me from getting that rear tire carrier) was that such forces could cause weakening or even cracking in the welds or in the metal - and that the catastrophic failure wouldn't happen while I was off-road, it would happen when I was flying down the interstate at 70mph and hit a pothole.
I love all the cool things people can put into receiver hitches, but I think it's important to remember what that hitch was designed to do.