Folks here all remember that airlines monetized checked baggage several years ago (its been what 10+ years or so?). Unfortunately, there is no data to show this and my guess would be that the data shows a low double digit increase in carry-on bags (10-30%) because of the policy to charge for checked baggage. When I was younger (my 20s) and had no status, I routinely used to check my roller bag even with a connection because I liked being able to board later and potentially be liberated from dragging a roller bag around. I had no concerns about the airline charging me for a checked bag. I am fortunate to have status now and cost not be factor. However, I hesitate to check my roller bag in not because I'll have to wait at the belt for 5-25 minutes (depending on the airport) though that is a factor, but primarily because I don't trust at all they won't misplace or lose my bag especially where there is a connection.

Ultimately, I place the limited bin space phenomena on the airlines. They charge for checked bags so folks are going to take whatever they can as a carry-on and the misplaced/lost bag rate (and subsequent hassle it creates) is too high.

I continually argue that if the bag you are placing in the overhead won't take up the space for a potential roller bag then go for it and go for it if you don't have a roller bag. Space under the seat is meant for feet...not bags.