I'm no immunologist, but this smells like horseshit to me. We've also evolved to (kind of) deal with cholera, typhus, the plague and malaria, not to mention famine and undernourishment, but I think we're better off without each of them, wouldn't you say?
That was my guess, thanks. Have people done projections of what effects our current behaviors will have on us ? Most of us are sitting, starring at a lighted screen for hours at a time. Will this have an effect on how our bodies evolve over time? I suppose this has only been a very short period of time in the grand scheme of things and could potentially be a short lived era, who knows.
You have to keep in mind that what we do has nothing to do with how we evolve. How we elvolve has only to do with how we produce offspring. So unless being a couch potato has a comparative advantage over not being one (in terms of likeliness of having kids), then I think it won't affect how we change in the future.