98roamer
Explorer
Personally speaking the size is my biggest issue. I've been hunting for a Coleman Colorado size popup (for two people and a dog) that comes in under the 1,000lb mark, can hold a weekend's worth of gear, and stand up to regular washboard dirt roads. The Somerset E2 mentioned above along with most pop ups currently on the market are too big.
Another factor is definitely cost... something like the Livinlite Quicksilver 6.0 or Jeep branded version comes in around the $6 to $10k mark. My current off-road trailer cost $2,500 without an RTT.
I have a Coachman Clipper 1275ST and the size is way too big (granted this was their largest model) and cost can get out of control real quick, when maintenance is factored in. Now my wife and I can set up the popup for just sleeping in 20 minutes (our best time) when we need to a quick overnight. They are just not made to do many offroad trips and still be usable. Cheap, light weight, durable; pick 2 of the 3
The popup model is just another solution for camping, not real popular but it fits a role. We enjoy the ease of towing and the tent like feel of camping, something you don't get in a Hybrid or a full travel trailer, IMO. We also get a Queen and King size bed with an inside toilet, so it's a base camp; here is the east we are pretty restricted to campgrounds anyway.