I have a motorhome and enclosed trailer.
The advantages that I see to my setup are many. As you said you can use it for other purposes. In my situation I like it because I only have 1 monthly payment. If you have a truck and long trailer, typically you will have 2 payments.
Aside from all that the motorhome with trailer turns better. Sleeps 6 at least usually. You can just pull over and sleep or eat. Your family or friends arent crammed in a truck while your driving. I dont know if it is legal or I would even want anyone riding in the trailer while your moving. You do have alot more room generally in the motorhome verses a living quarter trailer.
thats my .02....