Why not? I'm actually surprised some ultra-low LCC has not tried to crack the US marketplace. Have an ultra-low base fare and then charge for EVERYTHING else. Food, softdrinks/snacks, IFE, aisle/exit row seats, advance seat assignments, boarding priority, baggage, pillows & blankets, and everything else you can. Cram as many poor souls as you can into an A321 or 737-900. Do more advertising of products on board the aircraft; find as many ancillary revenue opportunities you can on board the aircraft.
I heard Ryanair has done way with stuff like seatback pouches and windowshades as well to cut down on costs too.
It sounds a bit loony but I'll bet there's a niche market below the level of service you get today from the LCCs currently out there.