Saving Social Security

I have never understood why a top limit is placed on wages subject to the Social Security payroll tax.  When you reach a certain threshold, which now stands at $113,700, you don’t pay into Social Security on anything above that yamount.  I’ve read that if the level were raised to $200,000, about 1/3 of the projected gap between income and payout would be filled.  That’s an easy reform for a large chunk of money.

Even better, why have any upper limit?  What’s the point of that?