Unfortunately, the solution is to board early, which is why many of us in bulkhead do.

It's a widely documented issue that bulkheads don't have enough seating since everything must go aboard. What do you suggest the FA's do? Stop someone in 2A/B from using the bin? Make them move their stuff back and leave the first overhead bin exclusively for 1A? What if it's full because of 1B? Tell them they have to put their stuff back as they have to leave room? There's just too many scenarios.

Aren't the bins in the front also smaller / used for a fire extinguisher also limiting their size?