On Spirit and Frontier's cheapest tickets you also get less legroom, no complimentary carryon to go in the overhead (which DL will check for free if they run out of room while Spirit will charge an arm and leg if you show up at the gate with a carryon that won't go in the overhead bin), generally poorer customer service, far worse IROPs recovery, no complimentary snacks or beverages, and no complimentary entertainment (unless you consider a fight that breaks out in-flight entertainment). If Sprit or Frontier are your cup of tea, have at it, and their model clearly works for a large number of passengers as evidenced by their overall profits. One just has to know what they're getting (and not getting). Me personally, I have yet to buy BE on any airline and I don't plan on buying BE due to restrictions imposed, but even with the recent changes I'd fly BE on DL before flying on Spirit or Frontier, even if NK or F9 would give me a handful of points while DL gave me no points.