The rewards for daily quests need to be used for something else other than just the battle pass. Daily quests keep players playing your game daily. If you can't use the reward for anything, players are going to not be incentivized to continue doing them. A player who hasn't invested in the battle pass yet, or a player who has the battle pass but has already bought everything in it, are not incentivized to continue playing every day. Especially if that currency is going to be going away in a couple months. Being able to spend it on proelium or having some cosmetics that you can buy with it would go a long way for retention.