I think this guy is pretty radically misunderstanding chile peppers -- he's British, and seems like he's seen them in the lab but never actually eaten one. Chiles DO in fact have nutrition, especially tons of vitamin C. They do in fact taste delicious outside of the heat factor, especially when combined with the garlic, onions, herbs and spices that they so often provide a base for, and they especially add deliciousness to bland (read: cheap) carbs -- hard to do otherwise in the absence of meat or fat. And I suspect that there is some antibacterial effect that helps make slightly less than fresh foods actually healthier as well as more appealing. So if capsaicin-loving is a mutation, you can totally see that it would be one that was helpful to humans and therefore passed on.

Yes it was helpful to humans in building our tolerance to pain, too, according to the WSJ:

http://pandawhale.com/post/56996/why-we-love-the-pain-of-spicy-food-wsj