Tam sums up why I'm so stubbornly opposed to government programs that everybody's sure are a Common Sense Good Idea:

...government gets big. There are two poles: Big government and No government. Being in favor of a little bit of government is like being in favor of the first trimester, but opposed to pregnancy on the whole.

You can craft, with the best intentions of the heart and the brightest minds in the world, a tightly-circumscribed severely-restricted government, and within barely three human lifetimes, you'll have an unrecognizable leviathan. How many times do we have to run this experiment to prove it?

You want government to seize your neighbor's property by force to pay your medical bills, and are sure you can prove it makes everybody's lives better. And I look at the countries with government medicine and see that they don't trust their subjects to keep and bear arms, and they prosecute people for offending others with their speech. And in my own country, whose Constitution demands a small federal government and respect for individual sovereignty, agents of government show a routine and casual disregard for the legal restraints on their power. City cops search people on the streets almost at will; you're sexually assaulted at airports as a precondition of exercising your right of free movement; my government is holding and torturing prisoners without charge or trial; our economic problems have been so entrenched through vote-buying and fearmongering on both sides of the aisle that they may be impossible to deal with; and the mainstream parties demand more, more, more government year after year... And it's hard not to think that maybe handing government the practical power to seize my neighbor's property to pay my medical bills is a really, really bad idea, however great the potential benefits.

You can't stop government at its most-beneficial point, because its nature is growth and bureaucratic entropy. When you fight for more government because you've decided that it's an inalienable human right to force other people to pay for your access to wundertechnology that was science fiction fifty years ago, you're enabling every tyrant and busybody who will use the same mechanisms of growth you've handed the government--but this time, they'll be telling you how you may use your own body, what kind of contracts you may sign, how you may travel, how much privacy you may have, what you may say, how you may conduct your sex life, how you may defend yourself, down to what year your ancient Italian coin collection must stop at...

Government can be slowly shrinking as the people fight against its growth, rapidly growing under its own power, or growing at a terrifying pace as the people hand it power to fix their problems for them. Those are your options. You can have government paying for your medicine, your education, and your rent; preventing development of wild forests; forbidding you to make agreements that it doesn't think are in your best interest; supporting unpopular art that can't compete when people have a choice not to buy it; and forcing people to leave their old houses unrenovated because you like the old-fashioned look of the street. And these things may very well improve the quality of your life. But the price of a government that cares for you as a parent is a government that controls you like a parent.

If ye love wealth better than liberty, the tranquility of servitude than the animated contest of freedom — go home from us in peace. We ask not your counsels or arms. Crouch down and lick the hands which feed you. May your chains sit lightly upon you, and may posterity forget that you were our countrymen.

...

Libertarian WHAARRGARBLE aside, much like Tam I'm not ashamed to admit that the ideal is unworkable. But fighting hard enough for the ideal of of a truly libertarian state might just--if I'm stupidly optimistic for a moment--get us to a place with a small, more-or-less controllable government that only flagrantly ignores the Constitution once a month or so. That possibility, to be perfectly blunt, is more valuable to me than the promise that government will give me some of your money if I fall on hard times.