I think they were addressing the difficulty of the quest related to it's rating as a 2+ or a 4. Some 2s are soloable and some 4s can be done with just 2. Hence the comment on under/over preparing for a quest.
Actually now that I re-read what OP posted, he meant tuning down the diffculty of the quests over all. I thought by downtune he meant change the rating of the heroic 4+ to 2+ for example and keep the same diffculty and hence my comment.