Especially since the implementation and recent increases of checked bag fees. That caused people to take the biggest possible carry-on bags, take more overhead compartment space than necessary, and make it problematic for everyone else. The worst of it in my recent experiences, having been responsible when flying and checking my carry-on sized bag and limiting my carry-on to a simple backpack for my laptop and a few other small items, is arriving at the gate and having the gate agents making repeated announcements of, "We have a full flight today and are looking for N people to check a bag," where N is usually greater than 10 and has been as high as 20... and then they reward these people by checking the bag for free and moving them up in the boarding priority. If they'd reduce the allowable and then more strictly enforce the carry-on sizes, they might not have these problems.