Well, I don't disagree that a rock solid codebase is important in either environment. It's the cost of change that is usually at stake, like you mentioned, and that's why I'm arguing that flexibility is more important.than code quality in an agile environment, particularly at the beginning of a project when there are the most unknowns.

You're hitting the nail on the head about burning out though. I suppose it's just the way the cookie crumbles.