If only people weren't so self-absorbed about putting small items in the overhead bin in the first place. I was re-orienting a guy's bag yesterday (he had put it in sideways, using the entire bin, so his and mine and even another bag could have easily fit once I turned his around) and he rudely pointed out an empty space on the opposite side of the aisle where I could put my bag instead of touching his.
Just because you get on the plane first, doesn't mean you are entitled to inefficiently take as much space as you like.