I don’t remember what year it was revamped and made narrow. (Anyone?) And I don’t remember which city staffers were instrumental in the change. But I do remember hearing lots of complaints about it after it was done, eg, from farmers about its inaccessibility for large farm equipment.
I don’t use the Parkway during school rush hours so I don’t know if it works well during those times. But it otherwise seems to work and the traffic-calming aspects of a narrow roadway seems to work, too.