Don't you have to be enrolled in a qualified high-deductible health plan in order to open one?
Yes. But check the numbers, in my own case it turned out that the max out of pocket is the same. The only difference was that although the deductible is higher, it isn't outrageous (only $500) and I don't have the use it or lose it flex dollar guessing game to play. Plus my employer contributes more to the pot. Pretty easy decision to make IMO.
YMMV of course.