Bad for traders, but still okay for investors
I think a central misunderstanding by arm-chair market participants is how bonds work. Yes, just like stock, they are commodity that can be traded. The price is supposed to represent a value above or below the face value of the bond itself, based on expected cash flow over the remaining bond term, other investment vehicles that could be used in place of the bond, etc. So if you are a bond trader, as in you rely on buying bonds at a discount and selling them at a lesser discount or even a premium, then yes, a large drop in the market value of the bonds will tank your portfolio
But if you are a true investor, as in, you are looking for guaranteed fixed income over a number of years, this is probably the best time to buy the bonds. They are so discounted that a buy and hold strategy would net you some pretty profits, assuming you want to lock the money up. Since the 30 year bonds have a 3.9% rate and you can buy them for 85 cents on the dollar, buy and hold would get you a 17% return at maturity, plus the 29+ years of interest payments. Is it the best use of money? Probably not if you have a burning desire to grow your portfolio more quickly, but if you're 65, 70 years old and want to lock in some kind of return for at least the next 10 years (30 years is a long time for a tech company, but that cash hoard should at least take 10 years to burn through), there are probably worse strategies out there. And if you are buy and hold, there are a number of 3 to 5 year maturity bonds you can probably buy off of panicked traders, though the yield is less than the current dividend yield of the AAPL stock.
And there isn't the added heartburn of "will they, won't they" every time a debt ceiling debate comes up in the US Government.