PE offered a "cheap seat" and nothing to eat. Completely new idea at the time. Low fare also meant "old leased airplanes", "contract maintenance", and a generally safe but unglamorous traveling experience.
Jetblue offers nice new jets, leather seats, awesome service. Additionally, pilots and crews there aren't "waiting for something better" but trying to build their own new brand.
AirTran offers (IMHO) the nicest ride anywhere in the 717 fleet in business class. Service is as good as I've ever gotten in first class on AA, DAL, or NWA. New jets, great service, and again...nobody appears to be in a rush to the exits to other carriers.
I think comparing AT and JB to PE is like comparing a Volkswagen Jetta to a Yugo. Both are small, efficient commuter cars. However, folks LIKE their Jettas. They are sleek, stylish, and (from what I hear) pretty well made little cars that are fun to ride. Yugos were, well...cheap transportation. Simply put, folks would rather fly US Air or Delta than Peoples Express IF they could afford the difference. Now, I think load factors have demonstrated both AT and JB have their own LOYAL customers, who will choose them over other carriers given similar prices and schedules. Need to go to Paris? Well...Delta is where you need to fly. Need to go to Dayton? Orlando? Seems like a lot of people are quite happy skipping the majors to give their business to AT and JB.
Not bashing anyone--just saying I think the QUALITY of the LCC is much better today than in 1981. This is a different situation entirely.