I would suggest that pipes had small bowls because they were carried in your pocket, with your flat tin of Prince Al (or whatever), and you smoked it when you felt like it/had an opportunity.
It wasn't a hobby, or something you did to be "manly". Most smokers didn't have a lot of pipes - oh, I am sure that some did, but they were the exceptions that proved the rule - and most of them only smoked one blend. They were smoking as part of their day, not sitting down for long periods to listen to the radio (or whatever).