Very much understand your perspective on digital alternatives, but in the same way I keep a written journal, I can see why I would feel more 'involved' with a written commonplace book. Perhaps it's because my major use will be to capture things I wish to learn and reaffirm, or perhaps it's that I'm more likely to browse through previous entries as I'm capturing new ones. Up to now, I've used Evernote for this, but I'm definitely guilty of dumping content into Evernote that I have never read again, or very rarely review. I think if the 'barrier to entry' is higher (the effort of writing vs simply hitting a button), then I will be more selective in the content I capture, and more likely to review. Also, I just have a thing about notebooks. :)