They gave back curses and for some reason chose to give back corruption instead of ‘curse’ of agony. I feel if they game agony baseline instead, making it only stack to 5 for non-affliction then that would give curses at least a thematic use. You have a curse for more damage, a curse to increase cast time, a curse to reduce attack power.
Also Doom needs to be completely reworked. There is no way it will ever proc a doom guard, and the fact they made a talent dedicated to the spell means makes even less sense.