Some ppl saying "people asked for a more TBC feel. Whelp, they got it. Be careful what you wish for?" but thats not true
During TBC casuals was able to get good PVP gear by doing casual pvp like Random bgs.
And now for doing good in bgs pvp and world pvp you have to farm PVE for artifact relics to have highter ilvl on Artifact. And also you have to farm PVE gear for having 5-8% more stats in PVP.
And in PVP weapon templating is "bugged". System takes the real weapon damage into account and not the template value. So a Rogue with ilvl870 artifact have much bigger dmg compare to Rogue with 770ilvl weapon.
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Lorewise WOTLK was focused mainly on fighting 3rd party forces like Scourge, Scarlet Onslaught & Scarlet Crusade, Zul'Drak Trolls,Titans etc
And Horde & Alliance wasnt fighting each other much.
There is quest in Borean Tundra where you help Alliance commander by sending him back Alliance deserter as Horde character.
And in Legion Alliance vs Horde war takes big part in storyline.
Even npcs like Jaina,rogers and Genn spread hate towards Horde and during WOTLK Alliance commanders was giving thanks to Horde player for helping Alliance by sending them back Alliance deserters.