There are many good reasons to support the removal of the cap on social security earnings. These are: be consistent with the Medicare program which taxes every dollar; solve the long term funding problem for social security; establish fairness in how social security is funded: the current cap results in middle class being taxed at a higher rate than the wealthy; allow everyones payroll taxes to be reduced by about 1.8%; and most Americans support this plan.
According to the Social Security Administration, fully eliminating the cap on taxable earnings would be sufficient to close the projected Social Security shortfall over the next 75 years. This assumes benefits for high earners remain unchanged.