It may not be "their job", but whenever I see a FA refuse to help a passenger put a bag in the overhead because of risk of injury, it always makes me wonder how their going to assist us in the event of an emergency. Some of the passengers look a bit heavier than the carry-ons! (Though sometimes that's not the case )

I recently had an experience where the bin above me would not shut and the flight attendant asked ME to re-arrange the bags. And no, it wasn't my bag that caused the obstruction! With a little shuffling, I got the bin to close. But then I was her best friend for the rest of the flight! She made sure I had my meal choice (seated in 3C) and even gave me 2 amenity coupons. It's all about the karma.