When I was a diving instructor I saw lionfish all the time in tropical waters - Maldives, Thailand, Indonesia etc. I never heard of anyone being spiked at all - they are totally non aggressive so I see absolutely no reason to kill them. What are we going to do, kill all rottweilers and pit bulls and the like as they can be aggressive if threatened??
The ocean is full of many beautiful creatures - many of which nature has provided with a defensive mechanism which they will use if threatened - stingrays, jellyfish, trigger fish. There is absolutely no need to kill them when we can just take pleasure from enjoying them in what is their environment - not ours.
Matilda