I've had the same experience. And I hate how colleges seem not to recognize that.
I imagine that those are going to become increasingly popular. If you abstract it out, its basically a credential system for productive independent thought, which is sort of the whole point.
However, as someone who supervises independent studies regularly, I can also say: independent studies are by far the classes most likely to result in the student just not doing anything at all, which to some extent shows why autodidacticism is not universal yet. In a traditional semester-long class with two-times-a-week meetings, it's very rare for a student to literally do nothing. Most will show up at least some of the time, and do at least some of the work. But it's easy to put off an independent study, because you have complete flexibility, and don't have to do anything this week if other things are more pressing. Then you end up 90% of the way through the semester realizing you haven't done anything.
Some very good stuff comes out of independent-study projects, but the variance is large, and it doesn't work for everyone. As a supervisor, they take a disproportionate amount of management effort, just trying to track students down and prod them into non-procrastination.
I skipped an entire years worth of useless general ed courses to get my "requirements" to graduate out of the way at my college on 6 CLEP tests. I think the notes I took for those tests reading the wikibooks and wikipedia articles on the various topics on those tests were some of the best domain information notes I've taken. I also wrote them online, so pretty much all my K-12 notes are useless, but I gave my CLEP notes to my extended family with notes they need to read the material themselves but I did a bunch of work already.
I skipped out on 26 credit hours of 140ish for the degree. It basically allowed me to change my major a year in without impacting my graduation date.