It is a matter of personal preference and learning style (in my opinion) as to how much someone will get out of a lecture. Some people in my program probably choose not to listen to the lectures and they just read the book, notes, etc. and do just fine. Depending on the class, I actually find it beneficial to listen to the lectures because often the professor explains a concept in a different way than that which I am understanding, or provides examples that make certain concepts a lot clearer to me. Also, sometimes during a lecture, the professor will give you hints as to which concepts are important to know for their exam. Again it is up to the individual as to how much they choose to get out of a lecture.
btw...Creighton's program is not fully online....I am pretty sure that there are currently no fully online PharmD programs