I think that would suck because it would increase some peoples' taxes by almost 15.3 percentage points of their income.
That quoted statement is not correct. The typical FICA taxes are this:
1) 6.2% of income up to the annual maximum for SS from employee.
2) 6.2% of income up to the annual maximum for SS from employer.
3) 1.45% of income for medicare from employee, no limit.
4) 1.45% of income for medicare from employer, no limit.
Thus, only people above the annual maximum (currently $106,800) would be affected. And since the medicare part was already taxed with no limit, the increase would be 12.4%, not 15.3%. Finally, in some cases the SS tax is tax deductible. So, in reality, only income over $106,800 will be taxed UP TO 12.4% more.
The drawback: a subset of the population pays more tax.
The benefits: people realize that FICA taxes are bigger than income taxes and they fight for lowered FICA tax instead of just fighting for lowered income tax. The republicans have been doing America a big disservice by ignoring FICA tax rates. Also, SS would be fixed forever.
Reagan fixed SS in the 1980s for what was thought to be the last fix ever needed. But that fix used one assumption. That assumption was that 90% of income was under the income limit. The problem with SS is that assumption soon became false. Since the 1980s, the rich got much, much richer forcing more and more income over that limit. This is why SS is broken now. Putting the limit to an automatically adjusting limit to capture 90% of taxes would fix it forever. We don't need to tax all income at 15.3%, just 90% of it.
Note: for 2011 only, it isn't even 15.3% total. But I don't want to go into that much detail since that tax break is temporary.