They have a nice solid, flat base to sleep on and you won't wake up in a puddle if it rains all night.
I believe the set up on them is fairly easy too.
As an added bonus, you're away from critters. Especially nice in bear country.
I have awakened to find my tent set up area of choice has had a depression that I didn't notice.
It rained hard all night and there was a nice 2" deep puddle in my tent. Right where I was sleeping.
Have also had bears sniffing @ the side of my tent in the night too.
That's pretty spooky.