That's true, but the center isle balances access from the seating areas. With double seats in each side of the isle (in current buses), the window seat passenger only needs to climb over isle seat to exit. With a single row of (4-5?) seats, the passengers on the far end need to inconvenience everyone else in that row to get out to the curb.
Win in one area, but lose in another.
Also, since you couldn't move within the transport vehicle when the doors are closed, the whole vehicle can become a trap if the FWDs fail to open due to malfunction or accident.