I hear ya. As a visual communications professional, it stands to reason that I am a visual thinker. Yet I'm perfectly comfortable reading a book, listening to a lecture, taking notes, hearing a song, interpreting a graph, or role-playing a scenario (well, maybe a little less comfortable with that last one). For me, in the end, the reward is the knowledge obtained; and I will do the work necessary to obtain that knowledge if it is of use to me and worth the work.
In all of this discussion, we have left out one of the more obvious causes of students' failure to learn: some of them just don't want to learn. Whether they are in school just "get their piece of paper", or were lured in by persuasive marketing and aggressive admissions agents, or were pressured by family or friends...
For some, the failure to learn the course's subject matter is in service of a larger lesson learned: that they don't actually want to be in school. It's a tough lesson, and an expensive one, but for some it's just as valuable a piece of knowledge...And may even result in something more valuable than knowledge: wisdom.