Here's a very entertaining TED talk by Aubrey de Grey of the SENS foundation that covers among other things, reasons why we should work towards defeating aging.

So I'm going to start with why we should. Now, I want to ask a question. Hands up: anyone in the audience who is in favor of malaria? That was easy. OK. ... So we all think malaria is a bad thing. That's very good news, because I thought that was what the answer would be. Now the thing is, I would like to put it to you that the main reason why we think that malaria is a bad thing is because of a characteristic of malaria that it shares with aging. And here is that characteristic. The only real difference is that aging kills considerably more people than malaria does.

Aubrey de Grey: A roadmap to end aging