This decision by Spirit Airlines seems to be to be more in their corporate interests than in what is in the interests of their customers. MSP is not a small airport. But, it is experiencing airlines pulling out?
Sadly, that's pretty much always the case. It's a company, and the true goal is to turn a profit, not do what is in the best interests of the customer.
That is why I believe that airline re-regulation is needed. Not an economist, but, prior to deregulation, the airlines seemed to make money and the public was better served.
That couldn’t be further from the truth. Prior to deregulation, airline service was barely a skeleton of what we see today, and, inflation-adjusted, airfares were considerably higher. Yes, you got a microwaveable dinner for that much higher fare, but paying for a checked bag, economy plus, and a buy-on-board meal item still puts you much further ahead today than you would have been in the 1970s.
Meanwhile, airlines are posting profits in the billions of dollars. Airlines did lose a ton of money in the 1980s through the 2000s, but that can be attributed to a few factors:
First, in the 1980s, the airline industry was still adjusting to the deregulation era and hadn’t yet figured out how things would work. A few legacy carriers bit the dust (or were on their way to doing so) because they hadn’t figured out how to operate in the new model without regulation protecting them (Pan Am being a big one there). Then there were a couple of cases of corporate raiders figuring out that they could personally profit by raping companies for all they had and sending the skeletons of the company to bankruptcy (Lorenzo and Eastern, Carl Icahn and TWA). Other carriers started and failed because they hadn’t figured out a business model that worked.
Then in the 1990s you had the Gulf War which had the double-whammy of spiking fuel prices and depressing demand. Yet, most airlines had fuel-inefficient planes from the 1960s and 70s and were too slow to replace them. Incidentally, much of the legacy airlines’ fleets were purchased in the era of regulation, such as DC-10s, L1011s, and even domestic 747s. They could fly them profitably when fares were regulated and they didn’t have to worry about competition. When deregulation hit, smaller planes killed the larger planes in terms of economics on most routes, which is why a carrier like Southwest, flying only 737s, was able to take on larger competitors. It’s also why the number of domestic wide bodies significantly decreased when the first generation were ready for retirement. You used to see DC-10s and 747s on short hops such as Chicago-Cleveland, Milwaukee-Detroit, etc. But once the carriers dumped them, they didn’t replace them with other 300-seaters, but with much smaller planes.
The early 2000s had, of course, 9/11, which led to a couple of bankruptcies, and the fuel cost spike and economic decline of 2006-2008 was the last major negative event to hit the airlines economically. However, since then, and following the latest consolidation, airlines are more profitable than they have ever been (and this with the fares still being lower than pre-deregulation).
I’m not sure what you expect regulation to bring that we don’t have already.