@Markerrag -- And I bet a lot of people don't know that. I'm not sure about how accurate the placement of Easter is, but I do know that Christ was most likely born in the spring instead of on December 25.
But, as you hinted, the actually dates did not matter so much. Converting pagans to Christianity was the goal and early Christians did that job well.
And don't take that to mean that I don't think putting those essential Christian holidays where they are is a bad idea or a move that diminished the significance of the events observed.