If the airlines want to speed up boarding and deplaning, then the airlines need to enforce the size of the carry ons. I have seen way to many people try to board a plane with carry ons the size of a small trunk. Carryons are not meant to be the size of a checked bag.

If Spririt wants to charge for a carry-on then they should get rid of fees for checked bags.

What's next, charging $12.00 for a ticket, but then charging to enter and exit the plane, carry on luggage, checking lugagge, going to the bathroom, looking out the window, soda, snacks.