I rarely found class lectures to be useful when I was in college. The only benefit was they imposed some degree of structure, making sure the material passed through my brain at least once. I guess it's also worth something that it gave me a chance to talk to the prof, but I rarely needed that, and they had office hours anyway. In general, lectures were like textbooks on tape, except without the tape.
One thing they definitely were not is teaching. I can read the book on my own. Teaching is about interaction. Teaching isn't a broadcast-only script; it's a stream that flows and changes direction in reaction to the students. Teaching is the teacher knowing her students and customizing the presentation to them. She skips the parts that they already know and spends extra time on the ones that are hard. She uses different media and styles of presentation to adapt the material to different learning styles. There are frequent questions, extended explanations, digressions, group discussions, etc. The teacher embeds the relevant concepts in a context familiar to the students to help them understand. The teacher is available for one-on-one supplemental tutoring in case any individual is having trouble, to customize the presentation to an audience of one. Printed textbooks are one-size-fits-all 1 . So are lectures. Real teaching is something different.
It makes sense why things went that way. Lecture comes from the Latin verb legere, to read. The first universities appeared centuries before the printing press. Books were rare and expensive. Reading aloud was the only way to disseminate the information. It doesn't make sense why things are still that way. It would be a far better use of resources to focus on creating really high quality teaching materials that are widely used 2 , and allowing the faculty to focus on research and real teaching. The current system is just a waste for everyone involved.