The way I understand it, submitting Avatar alone was a bit of a risk -- even though the data was good, there was so much uncertainty based on the "goal posts" arguments made by Feuerstein and others. Positive Excellence data submitted alongside Avatar provides a more robust NDA for the FDA to review.
With the FDA you only get one crack at approval most of the time, so I don't mind the delays if they will help improve Anavex's odds of approval down the line.