A quick look in the lost/found section reveals 31 lost boards since 01 Jan 2008, and one lost girlfriend
This is a phenominal loss rate of about
one board per day

And these are only the boards reported lost on this forum. If each board is say worth an average of $1000 to replace new, thats $31,000 worth of kit been lost in a month.
Im still only a relative beginner to kiting, and one of those 31 boards was mine. I have read all the board leash threads on this and other forums, and seen the gruesome pictures too - but am not convinced that board leashes are all evil and wearing one will result in the inevitable hospitalisation as some seem to think.
Its all about risk management, and only taking on extra risk if the benefit of taking the risk outweighs the risk itself. In my workplace we constantly manage risk at meny different levels, and wearing a board leash can also be managed effectively. Just being out there kiting carries extra risk of injury than watching from the beach. The benefit is the enjoyment you get from kiting, so you have judged the risk as acceptable.
Wearing a board leash also carries a higher risk of injury than not wearing one at all, but then there is the risk of losing ones board. All we need to do is mitigate this risk by wearing an impact vest and helmet, and using a modern retractable leash. By doing this, you are effectively reducing the probability of an injury from occuring from say "probable" to "rare". Not jumping with a leash also reduces the risk injury. The risk of losing ones board vs being injured has now been mitigated - but not removed.
The benefit of wearing a leash is a massively reduced chance of losing your board should you become separated from it, and all the comments of 'learn to body drag' mean nothing when your in a strong current and the wind is the wrong way. In this case youve got no chance of dragging back to your board - as I found out the hard way. They didn't tell me this in my lessons

Finally, all risk is an
individual
choice. What is acceptable for one is not to another. All those who so strongly advocate against wearing a leash (especially when learning) are obvously risk averse, and I would hope they walk to the beach, because the risk of serious injury in a car accident is far greater than wearing a board leash with vest and helmet. Perhaps they all wear fame retardent racing suits, racing helmets and 5 point harnesses, and have their cars fitted with roll bars - as this is the only way to 'reduce' the risk of injury in a car.
There are plenty of freak accidents in all sports and even day to day life. Kiting is no different - leash or not. BUT, with 1 board a day getting lost - I can only wonder how many boards would have been saved in the last month if a leash had been worn ? I personally think the risk of beginners losing boards is much higher than injuries they will get from wearing a reel leash with the safety gear. Its just up to the individual as to whether or not they are willing to mitigate, and then accept this extra risk.