I don't think Blizzard has a clear idea of how to make a game that appeals to most people anymore. We have two competing ideas here:
A. A coherent online world that people want to spend their time in as a primary hobby.
B. A seasonal lobby game that briefly attracts people for new content and expects them to fizzle out until next patch.
These are two radically different ideas of the game, and they are incompatible with each other. Blizzard seems to constantly be doubling down on B and confused why they don't get the results of A.