This is the slowest, most control-heavy and enjoyable meta I've ever experienced. I'm so happy. I'm between 10 and 15 on ladder, and rarely encounter aggro decks.
It's my Deathrattle Quest priest up against
- quest rogues (who I'm 50:50 against)
- quest shaman (who usually beat me, but long after turn 10)
- quest mages (quest seems slow, I crush them before they can really line things up)
- hunters (some quest, some not, I win most of these)
- mirror matches, which get to like turn 20 and are SUPER Fucking fun and epic fights (and I have like an 80:20 Winrate)
No paladins, warriors, Druids, or warlocks. Meanwhile, if I try out Wild, all I see are these four classes.
I honestly haven't seen evidence of the meta so many of you are describing. Even the awful rogues seem defeatable half the time.
1. The mechanic only works with one copy of the quest in your deck. They needed to put the card in the starting mulligan and some quests like the Rogue Quest would create pointless rewards if you included two copies of a quest in your deck. So it makes sense to force it so that you can only put one copy of a quest in your deck.
2. By attaching the mechanic to legendaries instead of some other rarity like epic, rare, or common, that easily communicates that you can only put one copy in your deck. Otherwise they would have to create special exceptions to existing rules by creating special epics or special rares that can't be collected twice.
3. Blizzard generally uses rarity as a gatekeeper to keep mechanically more difficult or unique cards from being easily collected. That way, players will generally have to be more skilled or more familiar with the game as a whole before experimenting with something they don't know how to use. Quests are some of the most mechanically difficult, unique, and complex cards they have ever printed, so it does make a lot of sense that people should have an idea of what a card does before earning or crafting it.
4. Quests are also cards that do enormously cool things and it just makes sense for cards that special to be legendaries. Even if those other 3 points weren't necessarily true, that's just standard CCG practice. You want people to desire your rarest cards.
I'm kinda on board with points 3 and 4, but 1 and 2 can be done away with by having quests be a new rarity tier. They can be as common as epics in packs, but still be limited to one per deck. I don't think that would be too confusing.
On that note, they'll have some work to do in terms of communicating what happens when more quests are created. Will we be able to have more than one quest in a deck and go for two different goals?