I'm not one who has said I'd like to move to Costa Rica but from reading the link you posted it doesn't look to me like it is mandatory for their citizens to purchase insurance. Maybe I missed something?
It says it is available to all citizens and legal residents. It also gives the cost to affiliate with it. I take this to mean that if you want to participate in their public healthcare then you'd be able to buy coverage at a cost of 10-11% of your income.
The problem a lot of the citizens have with this health care bill they just passed is that the government will be forcing its citizens to purchase insurance. There will be no option, you either buy insurance or pay a fine and be harassed by the IRS.
I don't know about anybody else but I DO NOT go to doctors, ever, period. Therefore I have NO need for insurance.