Does it actually cost the airline more money to allow this? They already allow underseat luggage, where you can store even heavier bags. They were limiting the

Does it actually cost the airline more money to allow this? They already allow underseat luggage, where you can store even heavier bags. They were limiting the size of the bag unnecessarily (even though there is plenty of room under the seat for a bigger bag). I think they will raise the prices at first, but eventually they will find another way to extort money from passengers and having a reasonably sized carry-on bag will become norm.