it will be a massive update and in the long run is better off done this way than split up into several small, unstable patches that will mostly have to be redone anyway. You want subpar content fast, or excellent content at a slower pace?
Looks like you are the one who has no idea how fine tuning balance in games with a long lifespam work.
No matter how much content they can fit in just one big update, no mater how much QA testing they do, they are not going to make everything perfectly balanced in the first try. There will be things that need some tuning and it probably will take several updates to get it right.
The more frequent the balance updates come, and the more feedback they get, the more balanced it will be in the end.
Expecting them to release a magical giant update that will make everything perfect is a myth.