Some people might call them training wheels for kites.
Helps with Yo-YOs and with enough wind, a Fade launch with the kite on its back nose pointing towards the pilot. Also, they keep tension on the leading edge portion of the kite's sail (IMO very helpful).
Does not help with the Twist aka Sleeping Beauty Launch unless you do a slight rock of the kite to get the nose off of the ground before the launch.
Other than that, another step to set-up and breaking down your kite.