More on "Private" Social Security Accounts

Today, Sebastian Mallaby adds to the debate on "private" Social Security accounts, noting,

The contributions will be mandatory; the investment options will be restricted; and retiring account holders may be required to spend their savings on annuities.

If they truly are going to force retirees to buy annuities, it sounds like a disastrous idea. After extracting year after year of "management fees" for handling the account, the companies approved to manage these "privatized" retirement accounts will also be permitted to extract the huge commissions typically associated with annuities? If retirees are going to be forced to purchase annunities, why not have them purchase them from the outset? The system Mallably describes sounds like a recipe for legalized churning.