[angryprofessor]

One important fact you miss (and the author missed also). All US bonds are dollar denominated assets.

The dollar was hugely overvalued (and still is, but less), as a direct result of China (and others) buying all this debt. By the time we repay this debt, the dollar will be less overvalued. This means that China gave us a $1=100 yuan loan, and gets back $1=80 yuan (numbers strictly made up, interest neglected).

To push the analogy way too far, it's as if I bought stuff on a credit card, with payments due in AngryProfessorBucks (which I can print as many of as I want).

So in short, it's good for us, but sucks for China. We get cheap products now, and pay for it with low value currency later.