I sure read a lot of whining here (seems to be from instructors in particular) about the modest cabin space in the aircraft types generally used for flight training.
What I don't read about are the students and instructors saying how pleased they were to pay the extra to learn or teach in roomier planes... Cessna Centurion, Cherokee Six, Bonanza, or Rockwell Commander (which is spin approved for that element of the training). They just keep getting back into a 150, and complaining about it!
Then.... The student graduates from the "cramped" 150, and "moves up" to the Mooney! How was that for roomy?
Written by a proud 23 year C-150 owner, who is 6'3", 195 pounds. If I do feel a little cramped, and am flying when the depths of winter are behind me, I often fly with a door off (which I approved). The 150 is very roomy that way!