Getting endgame improvements doesn’t mean other parts of the game need to be sacrificed. As I said in a previous post, there is zero reason multiple facets of it cannot be improved at the same time. Gaming companies divide development and upkeep duties up amongst teams for each title.
For example:
Team A focuses on the leveling experience
Team B storyboards
Team C mostly writes the code for the other teams
Team D, E, F, and G are focused on class design and balance.
Being only an example, this obviously is not exhaustive. It is, if anything, a very simplified way of putting it. Now; each of these teams will have overlap, probably even some shared members, but they won’t all be shared. Their work will remain ongoing even as other portions of the game receive focus due to a more immediate need for changes.
Blizzard has shot themselves in both feet, their left hand, and an eye, an ear, and at least two fingers of the other hand at this point, but I have to assume they still have enough people on staff to maintain some industry standard practices.