The could change their system to allow for seat selection at the time of booking, but for some reason, they have chosen not to for now. There was a time when it would have been costly and time consuming to set up a program like that, but not any more. Once ground is broken on a new system as other airlines have already done, it's relatively easy and cost efficient to do. It's just Southwest's corporate mindset to maintain the status quo. If it's not broken, don't fix it. At their prices, they're going to get their share of the business and they know it. I prefer assigned seating also, but then I seldom fly with them anyway because of the limited flight destinations from Dallas due to the Wright Amendment.