I would agree that if you're in Y, you shouldn't put your bag in J. I haven't seen that too often myself. I don't think you're "entitled" to the bin right above your seat though... Some people do put their bags across the aisle so they can keep an eye on things. I try to board early to be able to put my bags above my seat but there are no guarantees. Let's not start about the people who try to stuff their bags in at the end without any regard for others' belongings !!!

The ongoing debate reminds me of people (i.e my in-laws) who think the on-street parking in front of their house belongs to them (or maybe that's just a North Vancouver thing)...