Daily missions have had the benefit of making the game more exciting for those who have reached the Generalissimo rank. For example, if the battle is not going well (i.e., the other team is winning), the "Earn 99999 XP points" might keep a Generalissimo still playing. Normally, Generalissimos tend to disappear fairly quickly if one side starts winning as there is no point of staying until the battle finishes (because they don't need any more XP points to rank up, and the money reward is usually way too small to compensate for the time lost in a losing battle). Having said that, some of the missions are too easy in terms of the reward. But the best solution is not to decrease the rewards but rather to make the missions a bit more challenging (for example, to require "Finish 1st" to be at least in a battle of 4 vs. 4 rather than 1 vs. 1). That would keep people playing & interested, especially if one has already reached the highest rank. Also, the developers could perhaps think of a few extra missions for Generalissimos that would encourage them to keep playing until the end of the battle more frequently. Or perhaps (and this is no longer related to Daily Missions) there should be a crystal reward for every 50 000 XPs (or something) earned once the player has reached the highest rank?

Excellent decision - hope the experiment becomes permanent!