Executive Producer Kate Paiz sent out the following letter to fans explaining the delay:
We've had a very successful Beta program with some of the largest and most active beta player populations we've seen since Moria. The amount and quality of feedback on our largest expansion ever has been fantastic.Paiz thanked players for their patience and promised a gift for all those who have pre-purchased the expansion. This gift will arrive around September 5th in the form of 500 Turbine Points and a bag of consumables.
Thanks to some great efforts from beta players, we've identified issues that we think need to be addressed before we can launch. In order to address those issues and meet our expectations for quality we're going to need more time. As a result, we've elected to delay our launch to October 15th.