As it currently stands FATE's offer by far the quickest and at the same time easiest way to level a DoW/DoM class to 50. While some players might prefer to run dungeons, camp monsters or do battle leves, FATEs eclipse all of these by such a wide margin in efficiency that many players feel forced to do them. So I propose:

Keep FATE exp exactly the same as it is now, but lower the FATE spawn rate to 25% of what they do currently. This will still encourage players to complete FATEs as they pop, but make it less advantageous to have 100+ people standing around waiting for them to pop and marathon racing from one to the next.

At the same time, increase mob base exp 10-20% to compensate and increase rewards for dungeon completions and leves in terms of experience.