I think the issue (or at least my issue as a card-carrying member of The Left) was that (a) at the time, we had a very different economic situation, and (b) objections to what the money was spent on. A lot of that debt came about because of things like not negotiating prescription drug prices in Medicare D and spending hundreds of billions and trillions in Iraq and cutting taxes in a way that disproportionately benefitted the well-off. If we were in a deep situation like we're in now or Bush was proposing spending that money differently, I think there would have been fewer Democratic comments about the debt.
>Maybe 90% Debt:GDP won't hurt too badly, but sooner or later as it rises, it will crater even our economy.
Nobody's suggesting that an infinitely high Debt:GDP is a good thing, but a lot of people were using R-R to argue that we had to prioritize debt reduction now as an emergency even at the expense of stimulating the economy or else we'd wind up as some sort of hybrid Greece/Zimbabwe mess within 5 years.
>It's about our Government's complete inability to get it under control.
I don't really know that that's clear. We've had a period of time where the budget deficits were run up to pay for a major (Cold) war and the tax reforms, and then we ran very low deficits and surpluses in the 1990s. We were basically set such that we'd run a surplus during strong economic years (as the Tech Bubble was) and a slight deficit in weaker ones. We made a series of policy decisions that harmed the budget balance (Iraq, tax cuts, bad policy in Medicare D) but even then, our deficits were still in the neighborhood of nominal GDP growth. So we're actually doing kinda OK, though obviously not great. Then we have the mini-depression, which (a) reduced GDP well below potential, (b) reduced tax revenues due to people making less money, and (c) caused automatic stabilizer payouts (food stamps, unemployment, disability) to rise. It's not like we've been pushing through un-offset new annual spending this last half-decade, beyond the original TARP and ARRA. So if the economy recovers, we'll probably start to level off back into 2005-era deficits, where the deficit/GDP < nominal GDP growth, causing the debt/GDP to shrink.