It's great way to control players from creating multiple accounts. I saw a comment from user the other day mention that daily quests were his/her ONLY way of earning in the game from their 50+ accounts (Yep, 50+). I guess it's kinda infuriating if you're a developer of the game to know that some people are cheesing it and not actually playing the game.
Quests potion abuse is truly a problem although they do help new players a lot. I hope they adjust the price though.
@xyr