lifting the payroll tax cap: unwise?

Mark Schmitt has an argument against solely relying on raising the payroll tax cap to shore up Social Security's long term finances:

the payroll tax is not a tax so much as a premium in a system of insurance. And the cap ensures that the insurance policy is basically a good deal for everyone. That's always been the bedrock of its political success. You might be able to get a better deal, in exchange for more risk, through private accounts. But no matter how you cut it, in general Social Security is a net plus for almost everyone, whether through retirement or survivors benefits. On the other hand, if you lift the cap, and people who make $120,000 are paying almost $15,000 a year in FICA taxes (including the employers' share), they would start to see it as a very bad deal. They would have to be alive and retired for almost as long as they were working in order to see a positive return.

Put another way, lift the cap, and suddenly all those "calculators" at the Cato Institute and even the real calculators start to look pretty ugly, and private accounts start to look a lot better, for a lot of influential middle- and upper-middle class people. When the privatizers come after Social Security next time, their job will be a lot easier.

Note that Mark has addressed the issue in a lengthier essay previously, and in the present essay, also makes the additional point that the payroll tax itself is conceptually a tax on work, rather than wealth, and thus serves to penalize the poor and disincentivize labor. He also notes that the tax cut for the top 1% is a better target, and points to proposals by the Center for American Progress and the New America Foundation as reasonable starting points for discussion of a better balance.