But what would be the advantages to calling it stupidity in a public debate? I'm skeptical that most people are not fairly entrenched in sophisticated positions on life extension, having argued the matter on several occasions in real life with people outside my own ideological circles. If you want to convince someone to change their mind to adopt a minority opinion, it's generally most effective to show that you've given the matter more consideration than they have, and to avoid any implication that you're unaware of or have dismissed out of hand any arguments in favor of their position.
While I've never heard anyone argue in those words that Japan is inferior to Zimbabwe because people live longer, there's no shortage of people who will argue that societies like Japan pose more danger to our planet than ones like Zimbabwe, because of the ecological impacts of a first world lifestyle. Longer lives would implicitly be an exacerbating factor. I'm aware of this line of argument, and prepared to argue against it, but if I proclaimed those opposing my position to be stupid without first addressing it or any others they might bring up, then it would tend to give the audience the impression that I had not given the matter adequate consideration, was entrenched in my position, and prepared to rationalize away any arguments against it.
I tend to think that different techniques are needed in the public debate depending on circumstances. Sometimes it is better choice to argue carefully and to show considerable interest in your opponent's arguments, but sometimes the better way is to confidently declare your position as the only sensible one. People like Dawkins are not popular by chance, their style of arguing has some appeal.
Unfortunately I am not so good at telling which strategy works better for a given audience and situation.
Last Wednesday (2010 Dec 01), BBC Radio 4 broadcast a studio discussion on the question: "should we actively try to extend life itself?" The programme can be listened to from the BBC here for one week from broadcast, and is also being repeated tomorrow (Saturday Dec 04) at 22:15 BST. (ETA: not BST, GMT.)
All of the dreadful arguments for why death is good came out. For uninteresting reasons I missed a few minutes here and there, but in what I heard, not one of the speakers on any side of the question said anything like, "This is a no-brainer! Death is evil. Disease is evil. The less of both we have, the better. There is nothing good about death, at all, and all the arguments to the contrary are moral imbecility."
Instead, I heard people saying that work on life extension is disrespectful to the old, that to prolong life would be like prolonging an opera, which has a certain natural size and shape, that the old are wise, so if we make them physically young then old people won't be old, so they won't be wise. Whatever cockeyed argument you can construct by scattering into a Deeply Wise template the words "old", "young", "wise", "decrepit", "healthy", "natural", "unnatural", "boredom", "inevitable", "denial", I heard worse.
If I can bear to listen again to the whole thing just to check I didn't miss anything important, I may write something on their discussion board.