Note that disc media tends to degrade over time. After a couple years on the shelf, some DVDs become unreadable. This is typically not a problem with hard drives unless you expose them to fluctuating magnetic fields fairly frequently. I love alliteration.
Anyway, I don't quite understand why you would prefer to use discs to store your media when hard drives provide more reliable storage (both the writing process and keeping long-term integrity), more storage (a 2TB 3.5" external HDD costs about $120 now, and a 1TB 2.5" costs about the same) for less money per gigabyte. Not to mention the external HDD doesn't need a burner, which costs even more money, easily more than a 2TB drive.
The main disadvantages would be single point of failure, and lack of "physical feel," for lack of a better term. Single point of failure means that if your drive dies, everything is lost, instead of just losing what's on one disc when it fails. This is why people keep backups of data. By "physical feel" I mean you don't get to flip through stuff with your hands, and instead have to click through folders/directories, but I don't think this bothers most people.