I can tell you exactly why: these cities aren't places senior management want to live. I know this because I've worked for three companies over the years that have moved technology centers from cities on that list, to places like NYC & SF. The labor cost increase didn't seem to bother them, nor the price of real estate.
What happened was the company hired a new CEO, the new CEO hates living in Smallville, USA, and creates an initiative to relocate the company back to where they want to be. Ostensibly, this move is part of plan to improve technical innovation. They all claimed that coastal workers were superior to those from the Mid-west. Whether because they are higher educated, have more exposure to cutting edge technology, or whatever ("[SF, NYC, Dallas, etc] is home to (famous university/tech company"). It's pretty obvious what the real reason is, as the new executives are the first people out the door.
The only way to keep these companies is to either force them, or make the region desirable to rich people.