Idea is to make all raids of past available live -not time walking- simply tuned for live game play. Same mechanics just more hp/harder hitting spells.
Purpose: It could appeal more to people who enjoy all aspects of raiding and rather play mechanics of older raids. Some of those raids where incredibly fun!
Gear: Drop the same gear they did then but tuned to live content.
I realize set bonuses are gone and you can't have them drop BiS strength .. Or can you?
I can only speak for myself and my friends whom I know well in guild. We have a number of hours to enjoy wow per week, given the choice between Heroic/Mythic current content and Heroic/Mythic older raids (Kharazan/Ulduar as examples) we would take raids of past every time.
If they are tuned as hard as live, why not drop same strength gear?
What if you give those who rather go the azerite/corruption route what they want AND those who rather go vanilla tier set what they want?