I prefer the unhedged call option analogy: http://www.m3p.co.uk/blog/2010/07/23/bad-code-isnt-technical...
- Debt is predictable: if I know the price in the future, and the rate of interest, I know the price now. If I knew what the cost is going to be in future, I could come up with today's price for the bad code and make perfect decisions.
- Unhedged options either blow up (incur a large future cost) or they expire worthless (I escape without paying anything). I don't know in advance which outcome will happen, so in today's price, I have to consider both possibilities and factor in the uncertainty.