I am of the same opinion. When the game was first released a lot of players and reviewers were asking 'What's the point??? Where's the purpose???' and the excuse has been 'pick up and play'.
PKing is the only game activity that doesn't require any level of investment or maintenance. This would be no different, it wouldn't be frequent and it's really not as though people are not going to do the quests. Rather, the biggest issue is that they'll all try to speed run them within a few minutes of release and complain they have nothing to do afterwards.
I don't think it will create a massive imbalance to approach quests traditonally. To me, it'd just add layers of things (hopefully enjoyable) to do before the end game content.