It is also marketing, they want to give the best chance for there module to be sold, if they release it today and there is some important feature that are buggy or not working at all, people will complain on the forum, people will make video to say that this plane is bad, and then, even after patching all the issues, people will have fear to buy it because of it reputation, they want to avoid a bad module and it's normal. ED, are in my opinion doing the right thing, complaining about a release date is less important for them than complaining about a buggy module