I definately agree that our future choices have to be different than our current ones... especially as America's demographics shift towards an aging population. At some point, there will be a higher risk premium on American debt. The thing is, that hasn't happened yet. Not even close. T-bill rates have been in a decline since 2007 (the chart in your link shows that). Now, rates are rock-bottom lows and have been flat since 2009. Even with the American credit downgrade...T-bill rates and hence the Fed Funds Rate didn't much move. Why? I think the answer is that investors believe we're still a low-risk investment. In fact, with the Euro crisis flamming and the low cost of the American dollar, I think the risk of investing in Amercian debt has actually decreased. T-bill returns have dropped accordingly.
What I'm trying to argue is that ideas like the Bush-era tax cuts, medicare prescription drug benefits, TARP, the stimulus, funding two wars, and the automotive industry bail-outs all seem more reasonable if the debt you take on has a 0% real interest rate.
I'll offer a heretical opinion: Right now, we're in a unique time. Inflation rates are at or above the interest rates on American debt. That means American debt has a zero to negative real interest rate. At the same time, the future road looks hard. America's population is aging and our infrastructure is crumbling. Global challengers (ok...really one challenger) to American military hegemony are growing. America's access to cheap energy sources is increasingly challenged. We should be using this opportunity to deficit spend while the real cost is essentially free to fund enabling projects/programs for the next few decades. When the real rate of our debt then starts to increase, we should shift to a more balanced fiscal policy. We're in agreement that change has to happen...we just don't agree when.