Because they would be getting into the legacy airline business...

Competing with people who already know how to do hub and spoke (sort of).

Attempting to merge their unique operational program with a separate system capable of dealing with all of the international problems mentioned above. Hard to a 20 minute cattle-call turn when you have to check passports and the terrorist watch list...pretty much impossible at an international outstation.

I think long-haul would be out of the question. Canada would be reasonable, latin America also possible. Actually they were in serious talks with one or more regionals about doing just that before the bottom fell out of the economy.

I admire them for being disciplined enough to stick with their proven formula.