Very sad. Just hope people don't start seeing kitesurfing as a dangerous sport because of these types of incidents.
I hope they take the danger seriously and get professional instruction. The amount of stupid behavior I see every time I am at the beach is beyond believable..
Having said that apparently he was a experienced kiter that makes it all the more important to take heed of conditions. He was out on a 15 meter when others were on a 10 meter apparently from what was said here.