This is very much the same argument that went around and around when states began to pass helmet laws for motorcyclists. Do I have the right to risk my own head injury? Do I have the right to ask you to pay for my care, when my head injury renders me dependent? This is a classic "it only affects the user" type of situation; helmet use has nothing to do with responsible riding or driving, but only with the consquences of an accident, and then only to the victim and his family -- and society, when it comes to costs.
It's a very slippery slope to start down. If it's illegal to ride a motorcycle without a helmet, should it be illegal to go mountain-climbing without a guide? Search and rescue operations are costly. Should it be illegal to jump horses? Christopher Reeves is an example of what happens when you do that.
But in each of these cases, there are tons of people involved in the activities who behave responsibly without legislation forcing them to do it. It's the unlucky or irresponsible few that draw the press and the ire of uninvolved people. It is the same way with diving. At the very least, hundreds of thousands of dives are done world-wide every year, with a very low incident or mortality rate. This suggests that the way the activity is being conducted is relatively safe -- whether that means avoidance of incidents, or good incident response systems, is something we just don't and can't know. A few people behave irresponsibly and cause enormous harm to themselves, their families, their friends, and sometimes to the businesses with which they were involved and the agencies who have to afford search and recovery efforts (and the folks who risk themselves doing them, as with the Vortex incident). The problem is that drunk driving shows us that you can't stop truly irresponsible behavior with rules. The people who grossly ignore common sense and normal procedure will ignore rules, too.
I would like everyone, of every age and involved in every activity, to take a sober and thoughtful look at how they do what they do, and whether they are utilizing best practices, and reasonable precautions for safety. But human beings being what they are, you will never see that. Too often, regulations cause inconvenience or expense to people who are already behaving well, and do nothing to change the behavior of people who are willfully foolish.