If the interest rate on the student loan is lower than inflation, then the student loan will be "cheaper" the longer you take to pay it.
This is now a very rare instance, but there were programs and loan consolidation opportunities in the mid-200x's that allowed savvy student's to convert their loans to have an interest rate of around 1.5%.
Right now the inflation rate is actually quite low, but it's not expected to stay there, and wasn't that low just a few years ago, so in the long run this type of debt will only be cheaper the longer it takes to pay off.
It is risky, as others point out, as it can't be written off in bankruptcy, but there are other situations where it can be written off more easily than other debts, so on balance the risks aren't better or worse than other loans in general. For specific individual situations the risk equation might work out differently, though.
Further, student loans aren't considered traditional debt by some lenders for specific lending opportunities, thus allowing you to go into greater debt for certain types of purchases. Whether this is good for you or not depends on the importance of the purchase. If you need to buy a house and the interest rate is higher than your student loan rate, it will be better, financially, to pay off the house first, while paying the minimum on the student loans.
If you have no other debt with a higher interest, and the student loan interest is higher than inflation, there is no reason to delay paying off the student loan.