As I said recently in another thread http://boards.straightdope.com/sdmb/showthread.php?p=20108354 the challenge is the airline itself, and the individual gate agent worker bees, are trapped between enforcing the rules which makes the whole process go easier but pisses off certain specific cheating individuals, or letting chaos reign while avoiding getting yelled at by some percentage of customers flouting the rules.
Social media has made things worse with sites dedicated to “How to game the system to get more than you paid for” and “How to take more than your share of what’s supposed to be shared resources (e.g. bin space) from your fellow passengers.”
So far I see a lot more praise for “Carrier X let me get away with boarding an excess bag” than I do for posts like “Carrier X prevented me from boarding an excess bag so everyone else will have room for their one bag.” Carrier X has lots of employees watching social media and wants to do whatever garners the most praise from the customers.
It’s really a race to the bottom going on. IMO/IME when jerks are less than WAG 2% they’re shunned and effectively suppressed by social pressure. Once they exceed WAG[sup]2[/sup] 10% they reach critical mass and it becomes maladaptive for anyone else to behave anything less than utterly jerkily themselves.
It’s not the doorway as such that’s the bottleneck. It’s the length of the line ahead of you. This is particularly true for de-boarding.
As you say, if you’re in the very back in row 30 you’re gonna be stuck there for 10 minutes since people only pull out their bags & offload at the rate of about 3 rows per minute.
If instead of all 30 rows going out the front door the front 15 rows went out the front door and the back 15 rows simultaneously went out the back door everybody would be done in half the time. Since everyone would be at most 15 rows from a door, not 30. It’d still be just 3 rows per minute per door.
The same effect could be had on twin-aisle widebodies if we also used the right front door for deboarding. As it is the single door is double width, but folks tend to still go through it single file or sorta 1-1/2 file rather than two abreast from the two aisle streams. Just like merging on the freeway, people slow down & goof around more than necessary rather than zippering the two lines neatly together. It’s apparently deep-seated human nature.