Since certain airlines have instigated a charge for checked luggage it very hard to find room in the overhead bins for all of the bags folks take on the plane. On the last two trips we were some of the last to board and had to leave our small tote outside of the cabin to be stored elsewhere on the plane. If all passenger only carried the correct size of carry-on there would not be much of a problem however some of the bags we observed been stuffed into the overheads were way too big and very long, others would just not fit as they too big all around. I am sure the airlines will have to enforce the size of carry-on bags to the allowable size, we take only a camera a document case and one small bag on the plane with our toiletries and a change of clothes, it is unnerving having the bag refused entry into the cabin because all the bins are full and hoping to see it again at our final destination with only a flimsy paper tag attached to it by staff at the last minute. The last time I was not prepared and left my car and house keys in the bag.
I know the airlines have to make a buck and the idea of charging is to limit the weight of baggage, however in the belly of the plane or overheads it is the same overall.