Think of it in more relative terms. The average iPhone user isn't going to be using a 4 character PIN, let alone a 22 character one. While the approach taken by Apple has a number of very real drawbacks, upgrading from no security to good (but still hackable) security is a huge deal.

This isn't going to keep the NSA out of your phone, but it will serve to keep the average smash-n-grab thief or other low-skilled random out of your phone.