The whole basis for this was the fact that the FAA administrator in Dallas, where Southwest is based, didn't have the authority to drop the original issue last year, it needed to go to a higher authority within the FAA for the matter to be finalized.
The grounding of the 43 aircraft on Tuesday and Wednesday was for a different reason, an outside aviation consultant was brought in to do an independent examination of the aircraft maintenance records for Airworthiness Directive compliance.
They found that a two page document to the FAA to perform an inspection in an alternate method, due to some eddy current test probes were back ordered from the manufacturer, and would not be available for about 2-3 months had not been properly filed with the FAA.
The CEO of Southwest thought it would be better to take the aircraft out of service, due to the other publicity, and take our punishment now and get it overwith.
These cracks that have been talked about, for the most part are not visible to the naked eye, that's why electronic test equipment is used, when the paint is stripped away, it's still difficult to see most of them, so we are not talking about 'gaping holes' you stick an arm through.
Cracks in fuselage 'skin' on pressurized aircraft have been a maintenance concern since passenger aircraft became pressurized.
For some interesting reading, do a search for the de Havilland Comet, the first passenger aircraft to be pressurized, and the disasterous results that occured with that aircraft.
A lot of people got on the 'band wagon' on these issues in a political sense as members of congress got involved that probably for the most part couldn't be to concerned about it, but election year is here, and they want to look good to their voters.
Major airlines have tried repeatedly to put Southwest out of business over the last 37 years on a level playing field, but it kept on going and growing.
Most people don't know or realize this little fact, Southwest in 2007 carried more domestic passengers in the US than any other airline, I think around 102 million passengers.
So all in all , there is some truth to the original accusations, but not to the extent that they were sensationalized to.
Similar problems have occured at other airlines over the years, this is not an uncommon occurance in the aviation industry.