John Cochrane has an excellent op-ed in the Wall Street Journal. It's regarding the mandate that all employer-provided health care insurance covers prescription contraceptives, but Cochrane does an outstanding job of explaining why health care coverage for foreseen expenses is a bad bet, including this great example.
The minute pills are "free," under insurance, the incentive for drug companies to come up with cheaper versions vanishes. So does their incentive to develop safer, more convenient, male- centered or nonprescription birth control. And by making pills free but not condoms, the government may inadvertently be contributing to an increase in sexually transmitted diseases.