Cheaper to build has to be the right answer. Fewer headers, less framing, no holes to cut, no windows to install. Provides better insulation.
I had a 2005 vintage Nash. It had the old window in the front with a cover, a window in the back in the aft bathroom, windows over the kitchen, the dinette and 2 windows by the bed. I go to the outdoors partly for the scenery.
Few modern trailers have decent windows and it is a crying shame.
The one exception is the rear dinette configuration with the 3 windows. Several companies make one.
