Crazy? Really? You think it's crazy to not use insurance for something I consider a trivial expense? I also don't insure for optometry care.
That $100 per year is constant. My dental care is usually less than that, even without discounts, and even when it's not, I can comfortably afford to pay for it out of pocket.
I think our culture of insuring for everything vaguely health related is a big part of the problem with our health system, as it takes the decisions out of the hands of the people best able to make them and puts them into the hands of bureaucrats. I'm certainly not going to contribute to breaking dental care by insuring for it, as well.
Anyway, I insure against serious problems, not against normal care. If I could do the same with health care, I would. I shouldn't need to go through my insurance company just to go in for a checkup. It's stupid that it's the way things are done...so I certainly don't want to have the same hassle with dental care (or optometry, or veterinary care for my dog, etc.).