Like I said before, I think we are a less risky investment now, relatively speaking, based on the fact others are more risky (i.e. the EU). However, let's not kid ourselves. The rate is deceptively low for another important reason. Since 2009, the Federal Reserve has been printing money to buy treasury bills and bonds at unprecedented rates, to the tune of over $2.3 trillion (see today's article: http://www.usatoday.com/money/economy/story/2012-08-30/ben-bernanke-speech-jackson-hole/57470268/1).
Unfortunately, it is difficult to translate this approach to entities outside the government, which obviously has the ability to print its own money. The closest example I can come up with is comparing this to a Fortune 500 company. This would be like Coca-Cola purchasing its products off the shelves of convenient stores in order to keep its sales abnormally high. In the long run, it is not sustainable. It is a ploy to prevent us from sliding back further into another recession, but at what cost to the future?
Sure, debt is cheaper today, deceptively cheaper as I've pointed out. Does that mean we should continue to finance projects, proposals, and policies with debt in the hopes of bailing ourselves out of a hole we dug for ourselves in the first place? I think it is a very risky proposition. In fact, isn't this also similar to financing a second home in order to turn a profit on your investment since financing is easier to obtain? That didn't work out so well in 2007 and 2008 for some Californians buying homes in Vegas and Phoenix. If we fund projects today that are not sustainable in the long term because of the costs required to maintain them and the potential for costs to increase, should we continue to go into debt because its cheaper or easier to obtain financing now versus later? That's assuming heavy risk for a very low return in my opinion. I don't believe it is sustainable either.