Seems to me that if I needed to take a pay-cut then I'd be better prepared if my costs of living were lower than if I had locked myself into the expensive city

Seems to me that if I needed to take a pay-cut then I'd be better prepared if my costs of living were lower than if I had locked myself into the expensive city house. "Just pack up and move somewhere cheaper" is easy advice to give, but it doesn't apply to every situation. Not everyone has that luxury. By the time you reach the mid-point of your career, you may have one or more of a partner, a partner with a professional career, personal obligations in your area, a mortgage, a mortgage you can't get out of without losing a lot of money/credit rating, aging parents, children, ailing family members who live with you, medical conditions which limit where you can live, ex partner with children not willing to move, et cetera. Alternately you may already live very frugally. When I was fresh out of college, I couldn't have imagined any of those circumstances applying to me or anyone I know. Now I've seen them happen to many of my peers and colleagues.