It's the same thing for most goods - the price mechanism is inherently value-neutral, and then whether it's better if prices go up or down depends upon how many people are potentially on each side of the transaction. Falling wages are seen as a bad thing, because most Americans identify with labor and not capital. The social security crisis is seen as a bad thing, because senior citizens (who get the payouts) vote in much larger numbers than young adults (who pay the taxes). Falling stock prices are seen as a bad thing because most Americans own stocks, even if indirectly. Falling CDO prices are seen as a good thing because most Americans do not own CDOs.