Trailers are great for bad weather camping, i.e. hunting or skiing. But then they have to be a little bigger than those tear drop jobs, so you can actually have breakfast and get dressed inside.
The major down side to a trailer IMHO is the 55 mph speed limit. I work Mon-Fri and if I want to get away for the weekend, driving time is important. It also can't be stowed in a shelf like the typical car camping equipment.
One day I will own a Sportsmobile and be done.
G