I would guess most TC's are used by a couple rather than a large family due to their compact size. Most people with larger cabs use them for additional storage instead of people. Class C's allow much more comfortable seating while traveling than a truck cab if you have more people in your party.
Right now I can remove my TC and the truck is 19' long and just under 7' high. It just barely fits many parking garages and I know would not be able to use a larger truck for such use. At some point the trucks become too large for city use or as an occasional commuter if you live in congested areas. It would be different if I lived in the country or did not work full time and have to commute daily to work or make business trips to other sites...
We went from bumper pull trailers and toy haulers to the TC for more flexibility in where and how we camp. We could do the same with a smaller Class C, but few offered such a small package that could comfortably tow 7000+ lbs behind them and have 4wd for boondocking and winter camping. Now we can haul two different sized garages (trailers) with us or leave them home when we want more maneuverability.
