The thing that convinced me to play World of Warcraft nearly ten years ago was pretty odd.
My college roommate was playing on his Orc Warlock - only about level 7, he was wandering around Durotar looking to gather linen cloth so that he could work on his tailoring. Strangely, I was inspired by the idea of having some righteous battle-mage (a character class I could swear does exist, but I don't know in what game) who makes his own armor. With a Paladin being the closest thing to a battle-mage I could find, I rolled up my first character and made him a blacksmith (a year or so later, having never caught up on blacksmithing after getting to Outland, Blizzard introduced both engineering goggles and the Flying Machine/Turbo-Charged Flying Machine mount, so I switched to engineering and have been happy with that decision.)
The thing is, professions have not really evolved in the way that other game systems have. They're still a huge grind and the end benefit is sort of underwhelming - it's rare that you can make a piece of crafted gear that rivals what you get out of raids or dungeons.
But even when you get really good rewards (and actually, while the reliance on daily cooldowns in Warlords was utterly obnoxious - essentially creating a problem so that the garrison buildings could solve it - I did appreciate that you could continually upgrade a piece of gear to the point where my paladin is still wearing the goggles he made back in 2014,) the process of making things is not terribly interesting - you just grab the recipes from a trainer (or a vendor in Warlords) and gather materials and make it.
In Legion, things will look a little different.
For one thing, your profession skill matters less - while Warlords allowed you to gather materials at a very slow rate regardless of your skill level, it appears that in Legion you'll be able to collect full pieces of material regardless of level - no more "ore fragments." You will still become more efficient the higher your level, but I'm hoping that you won't be super-penalized if you're starting a new profession (such as if you are a Demon Hunter.)
Learning a recipe will also not be the end of your work on a piece - you'll be able to gain higher ranks in each recipe (including gathering materials) that will increase your efficiency - gathering will yield more materials while crafting will require fewer.
Each profession will have its own quests as well - there will be quests you unlock as you level up, giving you tasks to complete in order to learn new techniques and recipes, and at 110, there will be world quests that depend on your profession. There is even a dungeon, the Court of Stars, where your profession might give you the opportunity to do something unique, granting your party a buff or helping to take out an enemy.
This will certainly complicate professions and probably make it harder to be a total completionist, but on the other hand, it is introducing more gameplay into the profession aspect of the game - probably not so bad of an idea.