Numbers 15-17

God wanted to help the people remember to keep his commands. So he created a reminder for them. Just like the reminder he created for Noah it was not only unique but also stylish and unobstusive. It wouldn't stand out as something rigid, but rather a gentle reminder of what God wanted from his people. I don't know if tassles existed before this time, but I wouldn't surprise me if they were something new that God created just for us.
Stuart