In general terms, I think much of the argument for breaking rules and carrying large amounts of or heavy luggage on to the plane has to do with a pretty self-centred approach to rules. Sure, some rules are a pain in the arse or can seem arbitrary, but what right does one have to decide that he in particular gets to break them? Would he be the same type who would sue the $hit out of the person whose luggage falls out of an overhead bin and cracks their skull? Or the type who kicks up a stink when all the bins are full of other people's ludicrous amounts of luggage?

"Common sense" means so many things to so many people, but could also include paying attention to the broader needs of a plane full of travellers!