This would make them loads easier to find, especially once you've discovered them. This way you don't have to cycle through your quests just to find the right marker in case you've forgotten what Kisnar looks like.
Additionally it would be kind of nice if you could have several quests active at once, if youre trying to do many at a time, so that you can see where you are relative to each nature spirit.
Edit; or as stated in another thread here recently, why not make an aura around the quest giving object that can only be seen once youve interacted with them as a QG?