The mask doesn't drop your light that far down when compared to the level of strikes it makes you do, my character is only 383 at best with very specific loadouts and he only dropped to 344 with a mask. I find this level enough to do heroic strikes. I may not like the way bungie structured destiny and how much better it "could" have been compared to what it came out as but I do like silly little events and quests that have nothing to do with the grind related to increasing your light