1. Listening to bad feedback from people that have no clue.
2. Lack of exclusive rewards for Harder Content. I recognize there is a need for difficulty settings, allowing people to see content, but there has to be significant incentive for Harder Content. The challenge itself is a reward for a lot of people, but we could use more. Titles and Mounts should only be attainable while content is current.
3. Designing gear progression in a way that LFR is part of it. I agree that LFR has a place and public and that it shouldn't go away, but it shouldn't be the only way. Heroic Dungeons (Premade only, with difficulty similar to BC) could have the same ilvl as LFR. Then we would have Questing Gear -> Max Level Dungeons -> Crafting/H Dungeons/LFR -> Flex -> Normal -> Heroic.
4. Adding flying mounts (There would be a need to provide a good way of moving around though. Better flying paths or NPC teleportation for a few important points across the map).
5. Removal of attunements instead of just removing the restriction aspect of it. I'd like them back but not like the old ones that restrict access. Just a huge quest chain involving personal challenges and different boss encounters across a variety of dungeons and raids, full of lore and cosmetics rewards at the end. It wouldn't affect your DPS or content accessibility.