Given the countless issues and countless posts that bin space has created, you would think people would come to some logical conclusions. The only problem with expecting logical conclusions is that you are dealing with people, many of whom think only in terms of 'me' rather than in terms of logical.
So what are some logical conclusions that could be reached if people were able to remove the 'me' factor from their thinking? Well, we could start with:
1. Bin space causes problems. Anything from 'up stream' behaviour to actual physical confrontations between people.
2. Potential solutions might be to increase bin space or remove bin space entirely and allow nothing on board that cannot be stowed beneath the seat.
3. If you choose to increase bin space, how much would you logically need to increase it and would it stop 'up stream' and other behaviour regardless of how much you increase it?
4. If you remove it entirely, what behaviour in regards to 'me' thinking would still be possible? Put your laptop bag under someone else's foot space to leave your own feet more room?
Frankly, the only logical conclusion I can see is that bin space should be removed entirely. I am quite sure the airlines know that and would love to do so. You can easily see how much quicker it would make loading and unloading passengers for example and the conflicts it would avoid. But no airline wants to be the first to do so. Why? Because all those who want to carry on luggage would stop flying with them unless every other airline did the same. The 'me firsts' rule.