Only one bag should be allowed (per pax) in the overheads. If you bring more than one, you lose your foot space, not me.
If you cant lift it above your head, its too heavy and should be under the seat. Your problem, not mine.
If its too heavy for you to carry and needs to be dragged along with wheels, it is too heavy and needs to be with the checked luggage
Quite simple rules really but common sense doesn't apply all the time airlines charge for checked bags.