Quests and quest-givers are there for those who care about lore and storyline and immersion in general. The ability to kill boars for gain is there for those who enjoy killing for gain -- and yes the two groups overlap. But when quests become nothing more than a transparent artifice to reward players for killing boars, then they no longer serve any real function as story-telling devices and they can end up actually hurting immersion.
Unfortunately, John is wrong. Not in that quests can hurt immersion. That's true. But in that quest givers are there for lore, storyline and immersion. Instead, quests are a very important loop that loosens up the gameplay. And they keep the player's mind busy.
As long as you consider running back to questgivers worthwhile and non-frustrating (you genuinely accept it as 'normal', 'god-given', 'the-way-it-is', it doesn't appear to you that you shouldn't have to do that), it adds to your experience. It is fun. Lore and the simulation aren't as important as the pure abstract gameplay.
If you don't believe me, then answer me this: How do you explain that millions of players over the years leveled for hundreds - often thousands of hours - to level 60, 70, 80? And all they did was kill-mobs, return to questgiver, kill mobs, return to ...
In Cataclysm Blizzard tried to make the story better. But it didn't really work that well, because more important than the simulation is to keep the player's mind busy. This coming from me you really should believe it :).