Monetization/Gameplay
The game is becoming more and more like a cash grab. Nothing, and I repeat nothing, should only be available on the store for real money only. Right now for example you can only buy the Fallout lands with money. I love Fallout but have no plan to get the lands. Everything should be purchasable with in game gold.
There is also no MMR in the game to speak of. Since when is it fun to lose 20 games in a row? Fix matchmaking. Better yet, get rid of win only game modes like midweek magic. Forcing players to win to get rewards only makes the game hyper competitive and frankly unfun to play.
Lastly, Magic is very fun and there is an opportunity to bring in more game modes. There is no 4 player format supported in Arena. 2 headed giant and commander/brawl could be really fun and I would highly recommend adding them to the game.