To be fair, there are a lot of of bugs or rather unscripted events when it comes to quests though. Many of them have been mentioned already, the Blue Tubers in Razorfen Kraul, the Missing Diplomat Quest event, the Marshal Windsor BRD Jailbreak event, the Putting Down the Banners D2 set BRD event, the RFD escort quest.
Sure this is all leveling content but I would argue that it is equally important to endgame content, missing these finer details takes away from the immersion. I don't want to advertise other servers here but I think this is a good example of paying attention to the finer details that made the game so well polished: