I included it because passwords don't need to be hard to remember. If they make sense to you and have a bit of thought behind them they can be just as secure.
I am not saying these codes are perfect but if they are the weakest link in your network of security it's a decent start. Someone could be trying to get your passcode for days but unless they see you checking something like the bar code of a notebook before you have it memorized they could spend months guessing before realizing a segment of your passcode is the number of a pizza place in your hometown. It's not exactly something that's going to come up naturally.
I mentioned it in another comment but they also lock you out after a set number of attempts preventing brute force attacks.
I am not saying they aren't overpriced for what you are getting ($100 for 8GB) and considering the other options that are available but I doubt they are significantly easier to crack than a smartphone