Required repayment through what, debtor's prison? Have you ever looked at the statistics on the percentage of court-ordered required child support payments that aren't being made?
When your irresponsible uninsured patient leaves town, moves out of the state, changes his address and leaves no forwarding address, gets a new alias, starts working under the table, or files bankruptcy, who pays the cost of his care? In an ideal world, I suppose, you could put your irresponsible uninsured patient on a payment plan for the rest of his life, but in the real world, you'd never collect. People do not practice medicine as an avocation, they're in it to make money. So, once again, those who didn't use the service would end up paying for "Mr. Invulnerable" through our taxes and through cost offsets.
So, what it really comes down to is how government coercion will be applied. Should we apply it by requiring the uninsured guy to get insurance, or should we apply it by forcing everyone else to pay for his care? There really is no third choice.