Actually, I have a thing about commuter-doors (1/3,2/3 or 1/4,3/4 or whatever they're called) being used on anything other than frequent-stopping, short-distance, commuter-type services. But you're right, I 'have a thing'. The end-doors on a 175 for instance waste less space than 1/3,2/3 commuter-doors. That means end-doors allow for more, or more-comfortable, seating, which is what you want if you are on a long, or longish, journey.Well Rhydgalad has a thing about end doors, but somehow I think a 387 with wide doors is much more suited to Airport passengers and commuters.
Of course you don't want long dwell times if there are stops every two or three minutes, and of couse commuter-doors are more suitable for short-distance commuter services. But why are commuter-doors seen as more suitable for airport passengers too?