Blizzard should do what Disney did and restart Canon.
Set a point in time: The end of Warcraft 3.
Institute new rules on lore creation:
1. Lore Department is set up/restructured to write Warcraft stories. Main game storyline is handled here, and some extended universe stories.
2. Create an expansive EU. EU can be used for minor gameplay features later on such as when new towns need to be added, or a leveling monster needs creating.
3. Gameplay follows lore except on crucial matters. This enforces RPG elements as much as possible.
4. Main storyline is always featured in game. Even good lore ideas in the "bad lore" era of the game seemed like dumb decisions because this was all esoteric and hidden from the main game.
5. Systematize principles for lore and aesthetics creation. These rules are: The RTS series is Source. Lore and Aesthetics expand on Source. L&A must be original, yet must be inspired. Player Reception is gold, Player Foresight is horrible.
6. World building comes on equal footing. Its important to make the illusion of reality as strong as possible while still respecting the fantasy setting.
7. Retcons exist only when an oversight or mistake has been made. They do not exist to push new changes. If major changes are desired, new material must be written to explain the changes that is consistent. For example, WC3 and Vanilla Paladins were specifically members of the Silver Hand. If you desire a Horde Blood Elf Paladins under these rules, you have to create a new reason other than Blood Knights. Yes they were cool, but they broke a lot of story.
Players will get the better lore they wanted, Blizzard gets a whole new income stream.