Originally Posted by
thegeneral
My guess is that it has to do more with FA's not wanting their carts or other passengers to constantly bumping overweight American fliers who start spilling out into the rows once all of the aisle armrests go up. I'm not sure why CO bought seats that do this. There also may be times when someone needs to move quickly up the row for safety sakes and people not using the armrest would be in the way.
That said, I have no idea why you would want to put up that arm rest and how that would lead to a move comfortable flight.
Having the armrests go up makes it so much more easier and safer to seat a paraplegic or other types of disabled customers. They can be slide off the aisle chair into the seat without having to be lifted over the armrest.
It also is easier to get out of your seat when the armrest is up. You can swing your legs into the aisle and stand up without holding onto the seat in front of you.