It seems like starting with Legion Blizzard began to make WoW less about the "competition" and more about the "journey" and the "fantasy". All of the titanforged RNG, legendary RNG and class imbalances are geared towards making each player's WoW experience unique - some legendaries change the way you play so much that you can build specs around them. Now, this doesn't work in a hardcore raiding environment since specs have to be perfectly competitive or they get benched, and when you have individual players' performance affected by legendaries to such a huge degree you are obviously going to encounter "issues". Now in heroic raiding you are never going to have to bench people based on their dps or healing or tanking since all encounters can be beaten in just an hour or two of progression by executing the tactics they way they are intended - you won't need to bench people based on their dps in order to cheese Cenarius or beat the enrage timer on Guarm. Consequently, it's alright when you have people with utility legendaries - you can even use someone with tankier legendaries to soak some mechanics and whatnot.
Same goes for PVP - some classes can be worse at fighting but better at scouting / ninja capping / anti-capping and it won't cause any issues. If arena was eliminated I bet the number of complaints about class balance would go down exponentially.
What do you guys think? It's a real trade-off between competitive gameplay and more class "fantasy" and "uniqueness" but would it really be bad for WoW's health in the long run?