This is one of those things that seems good on paper, but in reality it really didn't play out well in game at all. If immersion is an end goal of a development staff of an MMO, doing things that removes immersion (like adding quest tracker) into their base UI, kinda goes in a 180 against adding immersion in the game.
Imagine life with quest tracker. Mindlessly pick up quest, mindlessly go to dot on map, mindlessly kill mobs, mindlessly return to quest giver, mindlessly turn in quest.
Pointless and boring.
Now, imagine life WITHOUT quest tracker. No dot on map, no highlighted area on map telling you exactly where to go. Now, you have to actually READ the quest to determine where to go. The quest givers give clues in their quest text that helps you go where you need to, to complete the quest. You read the quest, and you gain a little insight as to WHY you are doing what you are doing for the quest giver. Immersion.
Immersion is what is greatly lacking in the game right now, and I would argue that quest tracker is a major reason why it is lacking today. Yes, there will be people who will just have "thottbot" open on the other monitor, but many people would still read the quest text and objectives to find out where to go in game.
Bring immersion back to WoW!