Boeing DID plan the 787 around passenger comfort, that was the problem. They wanted to give passengers wide seats (over 18.5"), so they went with wide seats in a 2-4-2 layout. Eventually, someone realized that it is cheaper to go 3-3-3 and the original seats were wide enough that adding an additional seat would not bring the width below 17-18". Same thing with the 777. Boeing designs the plane with wide seats in a 3-3-3 layout, but airlines do their own thing. Blame the airlines for adding the seats.