IMO absolutely nothing after WotLK is canon. And from TBC and WotLK only bits and pieces are canon. Vanilla was such a perfect setup to pick things up where WC3 left off, but then... yeah.
Blizzard from day one listened to the crybabies on their forums and this is why the game is the way that it is. They listened to people who want to have full epic/legendary gear without working for it. They listened to people who want to kill the biggest villains from WC lore without it being hard.
The people that Blizzard tried to cater to are the types of people who would literally feel offended if someone was walking around with better gear than them. They feel insulted at the idea that their character can't 1-shot Arthas and Illidan while giving Sargeras a noogie.
These were the """cajoowuls""" that cried on the Blizz forums 24/7 to make things easier and easier. Supposedly they were the majority, and the people arguing against them were grouchy nolifers. Turns out that those """cajooowuls""" didn't represent a tiny piece of shit from the WoW fanbase, and their ideas drove away everyone else.