Towing Issues: Traveling in a 5th wheel trailer, 5th wheel trailer, curiosity

Question
What states is it legal to travel in a 5th wheel trailer, and what reqirements most be met.

Answer
well here is a link to a info page,  almost all the way to the right side is ride in vehicle comments...

http://www.towingworld.com/articles/TowingLaws.htm


Now just out of curiosity, why would you want to ride in something that CAN COME UNHOOKED if things go wrong ??   I have never understood that part of it..