They're a university tradition. When universities were founded in the Middle Ages, before the invention of the printing press, books had to be hand-copied by scribes. Thus, books were scarce and very expensive. The few books that the college owned would be chained to a desk for safe-keeping. Today, with cheap books, universal literacy and 24-hour electric lights, students can read for themselves.
Some people still prefer to learn by listening.
Others prefer to read and study by themselves. Some people enjoy the social stimulus of learning in a group at a fixed pace, others prefer to work independently and to set their own schedule. It's a matter of personal preference and individual learning styles. An additional consideration these days is that many UH students live a long distance from the campus, have health problems, or have heavy work and family responsibilities. Distance Education offers these students more flexibility and control of their learning environment.