A small list with some points

Technical limitations: The game is showing to have problems keepings things up. This also leads to empty areas, low textures, low render distance of enemies, players, items in housing areas for example. If concerned about PC lagging. Make it an option to make the distance higher.

Viera/hrothgar: I don't think there is much to say about it. They are a mess and in next expansion it needs a fix with hats at the most.

Gear: Gear get's every even patch outdated to quickly and you build the exact same gear up as previous tier. Crafted gear on day one makes your hard earned gear instantly invalid. This most likely has to do with progression of Raid tier Ilvl or crafted gear in general.

Also on topic of gear: Missing content to dump the high end gear in. Not speaking of Ultimates. Just extra content like high end dungeons to make use of your (current tier) Ilvl 490/500 gear in.

Live letters: I love the live letters. The big issue were I walk against is that they don't live translate them. I need to rely on Fan translations from discords. The population is growing and more and more are watching the LL. They need a team to live translate it for AU, NA, EU people at least.