are the writers trying to be all mystical and point out the fact we are all doomed to repeat the same mistakes over, i doubt it is probably more to do with the fact that the perfect way to end the final season is with Turk and Carla and JD and Elliot in relavent coupling with each other, leaving the viewer with a warm feeling inside and a nice bookmark ending.
however, i'd rather see JD with the mother of his child and Elliot with the man who truly loves her in every way.
oh and my choice for the final episode next season is a future shot, end on the penultimate episode and then close things off with a and this is where they end up finish