SWA seems to be making a big push to upgrade their image, and I think this paint scheme is an important part of the push. Other things they are doing, that I have seen, is pushing local parties for their 30th anniversary (inviting Rapid Rewards members, etc.), upgrading their website and inflight magazine, coming up with a new style for their reward coupons, etc. (I even received an invite to go to a Trailblazer's game!...)
As I see it, probably the majority of people in this country have no idea how big SWA is and that it has, in fact, been around for 30-years. All this image upgrading is probably a good idea, and well-timed to surround the 30th anniversary, so long as it doesn't raise ticket prices. As for the paint scheme, as much as I love LUV, I have always felt their old paint scheme was "different" from the other, more mature airlines (who lean toward silver, blue, red, and white), and with that difference seemed somehow "immature". The addition of blue is smart because, perhaps, it implies a more mature and substantial airline. When UAL went to a darker paint scheme, heavily blue, a few years ago, I think it had the same effect: it made them stand out from the other airlines (especially the failure PanAm), and look more mature.