1) Get rid of duty-free shopping at airports. If your country sucks so hard you need to shop at the airport to find bargains, then go home and vote in some politicians who will lower your taxes.
2) CC should get over the fact that people need to carry on hand luggage. If airlines didn't lose such a high percentage of checked baggage, or didn't charge the price of an extra ticket for a few pounds of extra weight, people would be more willing to check it instead. There's a very good reason people are willing to roll or tote their hand luggage all over a large terminal...the poor service at the baggage handling end of things.
3) Understand that not everyone is a frequent traveler and sometimes even if they are, they must be re-directed when they pull their overhead bin tricks. As the aircraft fills up, the boarding gets slower, and then stalls when people can't find anywhere to stow baggage up there even if they carry-on only 1 item. Many times the bins are filled with smaller 2nd items (computer bags, purses, duty-free items, folded up jackets, etc) that could and should be stowed under the seat in front of their own by from people who board first, who have already stowed a 1st item overhead. I've been at airlines where the CC know there will be problems with a full load so they make PAs regarding stowing 2nd items under the seat to allow space.
(Frequent travelers know when they're being space-hogs, however, so it's fair game to crush their duty free shopping/computer bag/suit jacket if they've done this and you need some room, all in the name of speeding up the boarding)