Regarding your parenthetical, if the bumping is voluntary then, at least in theory, everyone comes out ahead. The airline makes more money, the person in a hurry who is willing to pay more money gets to his destination more quickly, and the person who isn't in much of a hurry gets to pay even less for their flight than they originally thought. It's like an auction for the seat after the fact.

Of course, this is only a good thing if the airlines are transparent about it, and offer enough compensation to bumped passengers for them to take it voluntarily.