Let me explain why I think people hate Mythic+:

- If you are a hardcore player grind BIS a massive pain and probably will burn out anyone.

- If you are casual Mythic+ will inflate the ILvL gear for stuff that doesn't need it. So, if you don't have anyone to team up and you missed the early rush is a GL HF for you.

However the idea itself is great, and under certain affixes, dungeons are a lot of fun to do. If SE can find a solution for those two problems it will be a nice addition to the game. Oh, and will be very cheap, what's expensive to produce are assets and mythic+ is only coding.