The more complicated changes tend to be with expansions because they often involve system reworks. What you are recalling is from the What’s Next information from the Shadowlands expansion. Here is the section, from the blog.
System and Rewards
With Shadowlands, one of our core design philosophies is providing players with a better sense of agency. We want players to feel they have a choice over the destiny of their character and the types of rewards they want to earn. To that end, here’s some of the systems and themes we’re exploring in Shadowlands:
Professions: We want to make sure that crafting professions have more options to create a specific item rather than making multiple items in the hope of one with just the right stats. Instead, you might craft an item with specific gems slotted in to make the item you want.
Weekly loot chest : We’re looking into ways for providing players with choices between multiple items from loot chests so that each time they receive an item from the chest, they have more of an opportunity to choose an item they find useful rather than waiting for another chance the following week.
Legendaries: We want to offer a way toward building a Legendary of your choice and imbuing it with powers that you’ve earned.
With the expansion, we want to step back and focus on class identity first over specialization identity. This means moving back some of the class abilities to all specializations that may have been moved into one spec or even restoring some abilities.
We’re still early in devising and refining these systems, but you can learn more in the Deep Dive panel.