They probably weren't anticipating the dire subway repair schedule when they made these plans. Yes, it would be nice if they could accommodate. Or even if the MTA provided shuttles up CPW instead of just telling people to walk to the 2/3.
I remember one magical consequence of the stubborn 8pm curtain time. In "Into the Woods" five years ago, the show began before sunset. After a solid 30 minutes of somewhat bright lighting the chime that begins "Giants in the Sky" rang and the whole stage plunged into darkness with a sole spotlight on Jack, and I realized for the first time that the sun had set. Took my breath away.