That is the question. There is no good answer forthcoming.
Maybe it is thought to be one of those selling points to attract students. But the overhead and ultimately the cost to the student to support it is prohibitive.
An argument is that the dorms are necessary for the CCs to remain competitive. Competitive with what? The parking lots are full so they are not lacking students.
And you're right about the costs. Costs both to the schools and to the surrounding communities.
What a shame — “If it ain't broke don't fix it.”
CCs are great!