Gary Becker has a good post on health care reform. Excerpt:

In contrast to employees who continue coverage by remaining with the same employer, individuals with their own health insurance plans sometimes lose coverage after contracting a serious illness, or by making too many claims. For various reasons, it is not possible for individuals to buy long-term health insurance, although what they want is protection against future major medical expenditures since it is uncertain how healthy they will be when they get older.

Bush's proposal to allow employers to offer portable HSAs is an important step toward providing such longer-term coverage for the many men and women who do not continue to work for the same employer, or who want to maintain their health insurance plans after retirement. If the ceiling on how much can be placed in these plans is raised to high enough levels, HSAs could cover all but the medical claims induced by major illnesses. Under present rules, individuals can have a health saving account only if that is combined with a catastrophic health insurance policy.

Can anyone point me to the "various reasons" individuals can't buy long-term health insurance? I could speculate about a number of possible reasons, but I'd be relying on purely anecdotal evidence, and I'd like to read something more conclusive.