Nowhere does it say that cost cutting measures or deep discounts were responsible for what happened to the plane.
In fact, according to Wikipedia: The 737 is operated by more than 500 airlines, flying to 1,200 destinations in 190 countries. With over 8,000 aircraft ordered, over 6,000 delivered, and over 4,500 still in service, at any given time there are on average 1,250 airborne worldwide. On average, somewhere in the world, a 737 takes off or lands every five seconds. Since entering service in 1968, the 737 has carried over 12 billion passengers over 120 billion km, and has accumulated more than 296 million hours in the air. The 737 represents more than 25% of the worldwide fleet of large commercial jet airliners.
Boeing is looking into the cause and until there are solid answers I wouldnt automatically assume cost cutting factors by Southwest are to blame.
In other words, until we know differently, it is possible that this could have happened on any carrier.
My cousin flies for Westjet and you would be shocked at the stories he has about his own company and their fleet of aircraft.
Also, Westjet and Air Canada regularly have discount seat sales that are in line with the American discount airlines. The only difference in price being the enormous Canadian tax.