I kind of feel bad for Blizzard. I understand it's impossible to please everyone, but man the vocal haters are LOUD.
The biggest complaint I keep seeing is that Legion is nothing but a lack of content hidden behind time gated content or boring grinds that are a grind for the sake of being a grind. These same people then talk about how TBC or other expansions were the golden era of WoW.
Take a moment and seriously compare each individual aspect of Legion to a past expansion, any of them, and be honest with yourself on whether or not Legion is better or worse. Let's compare TBC to Legion:
TBC had much more content that was gated behind rep grinds, quest chains, daily grinds, etc. Remember Skettis? The amount of dailies you could do to increase rep for many factions was limited, and at ranks like honored and revered, typically the only bonus was another daily or two to speed up the grindy process.
Heroics were more challenging than what Legion has even on the mythic level, but mythic+ dungeons solve that "difficulty" problem. Once you were able to clear Kara/Gruuls/Mag, then that gear was better than heroics, so there wasn't much reason to do them beyond the rep grind, which also eventually ended. Even with the reputation choices, only a few would benefit your character, as the gear or enchants that were unlocked were specific to either casters or melee or tanks or healers, so you picked the rep or two you needed and could ignore the others. At this point, you were grinding rep for the completionist aspect of it and didn't even have a chance at character progression!
What else was there to do in TBC that you can't do in Legion? PvP, 5man dungeons, and rep grinds through grinding and very specific subset of repetitive dailies.
Let's not forget that the leveling process in Legion blows anything TBC had out of the water!
Outside of the whole "grind" conversation: the gameplay systems were different, and sure, that can be personal preference on which is better. But the talent trees in TBC were truly something that you would paste a pre determined spec and then forget about it. Few classes had options that were legitimate options. In Legion, most classes have options with their talents that should be chosen for either ease of play (passives), aoe, single target, utility, movement, etc. Much more decision making. "But to respec in Legion you need the tome which costs a lot". In TBC you literally had to not only be in a city, but you had to talk to a trainer to respec.
I do miss some of the unique identity classes had in TBC, like shadow priests being mana batteries. I do think that the complexity of playing your class well in Legion tends to be more engaging than it was in TBC for most specs (not all), but this is one area that changes every single expansion, and some specs are better in any given expansion, which again comes down to personal preference. If there are any hunters out there who try to say TBC was better than Legion... stop lying to yourself.
I loved TBC. I was late to the vanilla party and was just hitting 60 when TBC launched, so it was my first real taste of WoW. I began raiding and even started competitive progression raiding. My nostalgia glasses don't turn to vanilla, they turn to TBC and parts of WotLK. But still, I have to wonder why Legion is getting so much hate for the "grind" of content. This is nothing new to WoW at all, and Legion (in my opinion) is much better than any past expansion with their execution of it!
I'd be curious to hear legitimate counterpoints. Maybe someone can extend the look to other expansions in comparison to Legion (the outcome will be close to the same).