Every college sport except "big time" basketball and football have small crowds. So what!!! What is your point. How many spectators are at Div 1 baseball, hockey, cross country, volleyball, softball, track, rugby etc. The kids play because they enjoy being student-athletes.
Having attended a school with a then top DIII hockey team, every home game I attended (which was every one) had a full or near full arena - granted these arenas are in the 2 - 3K range for capacity, but that is way beyond friends and family, and for many DIII schools, those numbers exceed the student body population. Most of the away games I attended were similar situations - for reference this was the ECAC. I have to think DI hockey equals or exceeds the interest exhibited by DIII (my schools team is now DI, and they still fill their arena regularly). I can't argue about the rest of the sports mentioned . . .