Steven Landsburg argues in Slate that Terri Schiavo essentially stopped living years ago, and that it's now "frivolous to care about what she might prefer."
His cost-benefit analysis shows no value in a husband honoring a wife's wishes: "while I'm alive, your promise to enforce those preferences is unlikely to change my behavior in any socially useful way." He makes the same argument about a spouse's wishes for treatment of her remains; a corpse is no more important than a toaster, the headline implies.
There are many obvious counters to this. Many of them are variations on the idea that Landsburg's approach devalues a person while she is alive (and conscious). If I promise my wife I would bury her in a plot next to her parents, and if that's an important thought that makes her life seem ordered and connected with those of her family, what would it say if I broke that promise after her death? It would say I had no respect for her.
Separate from such moral arguments, there are serious costs which Landsburg seems unable to notice. Namely, that if people routinely broke such promises to the ones they ostensibly love, and if society let them get away with it, then there would be a collapse of trust in family life. You'd likely see more people staying single, more couples divorcing, etc. It could easily have the same disruptive effect as Landsburg's example of failing to enforce wishes in a will.
But Landsburg wants to find a reason to prevent Michael Schiavo from preventing others from keeping Terri alive. He cannot find any "legitimate" (my scare quotes) economic basis for this (i.e., cost-benefit analysis). He just feels uncomfortable about people keeping other people from doing something that doesn't much harm them. His analogy is censorship; he recoils from it, although economically he can't argue against it.
Isn't this strange? When it came to Terri's life (she's still alive at this writing), and Terri's wishes and best interests, all of that can be thrown out as irrelevant to a cost-benefit analysis. But when it's something that Landsburg has an emotional (and non-economic) response to, his recoil is a sufficient argument.