They do not give enough xp for the time/hassle it takes to do them.
They should be sending you to actual DUNGEONS for that level range with the object of the LEVE the end boss of the dungeon. Make it so that others with that LEVE get paired up so there is actual incentive to do dungeons + combat Leves as a viable way to level up. This would solve alot of issues, 1. gets more people into dungeons where they actually there is an incentive to PLAY well 2. reduces all the FATE grinding by giving an alternate way to xp that is just as good or better than FATEs where they can actually gear up for their level.