They're:
Light to tow
Give you a chance to get off of the road and have some fun
They're easy to mount the tow bar attachments to yourself to save money
If you get one with the rectangular tail lights, you can wire the tail lights with separate bulbs using a kit from Roadmaster so you don't have to hook into the Jeep's wiring and then you won't have a dead battery on the toad.
Because there's so many of them, you can often find a good used towbar, and maybe the connectors, on Craig's list to save money. That's where mine came from.
They sit high enough behind the MH that usually rocks from the MHs rear wheels won't hit the Jeep above the bumper. I put Lexan headlights in mine and it's been fine. We came down the Alcan with it.
And if you get the MH stuck, you can pull it out with the Jeep - well, maybe not.
The Jeeps are very easy to hook up. One person can do it.
I don't see any advantages to towing on a dolly unless you have a car that can't be towed four down and you can't afford one that can be. Dollies take more time to hook up and then you may have to move it to store it someplace.
Bill