Cost of Living is just one factor to consider, and everybody has different priorities.

I discount the CoL "bonus" because of the generally poorer environment with respect to culture, public institutions like libraries and parks, and educational opportunities. I grew up and lived in the south for most of my life. With precious few exceptions I found it to be mainly a canvas upon which the bigoted (race, gender, sex orientation) and extreme anti-government types painted most of the landscape. You could give me 100% of my current salary/year tax-free in a high-yield/low-risk investment account and I wouldn't move back to one of those places. I may have considered it before I had kids, but not now.