by Paul Krugman:
The usual argument against means-testing — which is entirely valid — is that it (a) doesn’t save much money and (b) messes up a relatively simple program. The reason it can’t save much money is that there are relatively few people rich enough to be able to afford major cost-sharing. Meanwhile, the good thing about Medicare, as with Social Security, is precisely that it doesn’t depend on your personal financial status — you just get it. Means-testing would turn it into something much more intrusive, like Medicaid. The third point is, if you want the well-off to pay more, it’s just better to raise their taxes.