To helmet or not to helmet

The sudden death of actress Natasha Richardson on the ski slopes of Mont Tremblant are adding some serious fuel to the debate of whether or not skiers should be forced to wear helmets while on the hills.
I have a bit of a hypocritical view on the subject, because while I think that people should wear a helmet skiing/snowboarding, I have never -- with the noted exception of when I used to race and helmets were mandatory -- worn a helmet skiing. I probably never will wear one skiing, unless of course I am required to do so.
I can't really defend my defiance here as I really can't think of an argument that would justify my not wearing one. If I had to, I would probably say that because I fall under the category of an advanced skier, the odds of me tipping over and knocking my head on the ground (such as was the case with Richardson) are likely slim. I've taken some pretty nasty falls in the 20 or so years I've been a skier, and never once have I been worried about suffering a head injury. In fact, when I've taken big spills on a ski hill my head is usually the last of my worries, after worrying about breaking a limb or my skis. I don't glade ski (skiing around trees) so I'm not too worried about crashing into a tree. If I did glade ski, I would most definitely sport a helmet. I don't do any kind of intense ski jumping, either. So I feel that, while I probably should wear a helmet, the risk of me cracking my head open on a ski hill are relatively minimal.
So this brings me to my point and my thoughts on the idea of forcing helmets on skiers. Don't. But there should be some system in place where skiers of a lower skill should be made to wear them. Richardson was apparently a novice skier, was skiing on a beginner run (I've been on the run in question, and it is about as flat and harmless-looking as it gets) and it sounds as if she more or less tipped over and hit her head. As it is, the odds of such a fall causing a fatal head injury are slim, and the odds of an expert skier falling that way are likely even slimmer.
So for experienced skiers comfortable on any run, helmets should be a personal choice. For anyone else though, I don't dispute that helmets save lives and therefore should be worn by the less experienced.