Secondary Stats
The way primary and secondary stats have played out is one of the regrets about Legion.
It is fine to have a best stat and worst stat, but items that don't have your best stat shouldn't be worthless.
This is something the team wants to fix, but it will be done slowly and with plenty of notice.
Players shouldn't feel that their item selection choices are suddenly invalid.
The secondary stats carry much more weight than primary stats right now. Some of this will be fixed as item level goes up.
Item level should determine upgrades. This is especially bad with the personal loot trading system being based on item level.
The team will continue to work on making things better here over the course of the expansion.
Why? It feels great. It forces the RPG to be an RPG, understanding how your stats work, and the implications of them. It has allowed for some of the most RNG heavy classes (and thus not fun) become less RNG. As fury I no longer have to rely on crit because I can stack massive amounts of haste. The class is fun. I don't feel like mastery is a worthless stat anymore because its so dependent upon enrage which is dependent on crit. I feel this was there best iteration of stats yet,even versatility has its use now. Of course though, anything that is fun and actually makes the game better must be seen as bad it seems.
I've always been of the opinion an ilvl upgrade, should not be a dps upgrade. It's far too simplistic of a system and really destroys loot as a whole.