Okay, for ya'll who didn't like my first answer...

There are three reasons why we shouldn't have a debt limit:

The first involves Section 4 the 14th amendment which guarantees the US will pay its bills... That's the legal reason...

The second is that, as we saw last year, even the threat of default causes our credit rating to be downgraded which hurts the general health of our economy... That's the economic reason...

Lastly, it is Congress that votes on all expenditures, not the president, and therefore holding anyone other then themselves responsible for paying those bills is just wrong... That is the moral reason...

B~