First, https://us.battle.net/support/en/article/21518 has, “You can submit feedback and suggestions…in…Our community forums…” “Community forums” is a link, but it links only to the main forums page, not a specific feedback subforum, not to instructions on how to indicate that something is feedback, and I could not, in a reasonable amount of time, find a relevant tag or a better subforum. So, this is written with a Blizzard rep. as the intended reader, but I welcome useful feedback from other players.
Main point: You’ve lost a paying customer because you chose to make a Dragonflight campaign quest require a rare drop. If there’s anything that shouldn’t require grinding/farming, it’s campaign quests. It doesn’t matter which quest, although I already submitted a ticket if you want to check. Don’t do that with any campaign quests. This overall kind of thing has changed in some games. For example, Elder Scrolls Online now has what they refer to as “curated drops”. They added a Collections system, through which you can reconstruct items you’ve gotten before, and when meeting related objectives, you always get a reward that you haven’t already collected. Probably pure coincidence, but they announced this system a few months after I made a similar post in their forums.
Big picture, be absolutely certain that when you set drop rates, you are considering the number of people who play the game. When it comes to probability, you must do the math. IIRC, the author of Innumeracy wrote that human gut feeling is “abysmal” when it comes to probability. Considering the number of people who play the game, when you roll the dice that many times, the odds of completely screwing over at least one person can get very high, and it’s not okay to do that even to just one of your customers, at least not when it comes to campaign quests. IMO, screwing someone over like that should be possible only with stuff that is purely cosmetic, and even that is debatable.
When you also consider that glitches do happen, it’s better to use a different approach when you want something to require multiple kills (or fishing attempts, dungeon runs, etc.). There needs to be a maximum number of kills (or whatever) that it takes to meet an objective. One way of doing this is that instead of a single, rare drop, make it something that you always get at least one of per kill, and if you want to introduce luck as a factor, make it possible to sometimes get more than one. This way, players will see that they are making progress, not encountering a glitch. This also allows you to set a minimum number of kills, something you probably want. Luck works out better if the minimum number of something to drop is higher. Getting two of something instead of one is twice as much luck, too big of a difference. Getting six instead of five is better. Set the minimum and maximum number of drops per kill, and the number of drops needed to meet the objective, in accordance with your desired minimum and maximum number of kills required to meet the objective.
If you want the objective to be something that an opponent has only one of, like a heart (usually), then make it always drop from a special opponent that appears after the player presents enough teeth, claws, bones, etc. at a certain location. Wisely decide whether they should have to gather another collection of parts to try again if they fail to kill the special opponent.
Some people seem convinced that many such things in the game aren’t totally random, that there is something going on behind the scenes to make sure that people don’t get screwed over. If there is, make sure that when two or more quests require different items from the same type of opponent, the system operates independently for both types of drops. If you intentionally want it to not be independent like that, make sure that you prioritize campaign quest drops.