Wizards of the Coast's latest Magic: The Gathering banned & restricted list update was a massive one, banning Oko, Thief of Crowns in Standard alongside two other green cards while also eliminating Wrenn & Six from Legacy, a format that had been dominated by the two-mana planeswalker ever since its release. Magic: The Gathering has been much more aggressive with its bannings as of late, and that's partly due to the fact that Wizards of the Coast has been printing more obviously powerful cards that are meant to impact formats beyond Standard.
The issue, of course, is that those cards tend to be too good for Standard as a result. In the case of Oko, Thief of Crowns, the planeswalker has widely been viewed as one of the most oppressive cards ever printed in Magic: The Gathering history, worsened by the fact that its only natural predator, the Golos & Field of the Dead deck, was banned out of Standard previously. The last Mythic Championship was utterly dominated by Oko and the color green in particular, with more copies of Breeding Pool - a Green/Blue land, the color combination Oko is in - being registered than basic Mountain, Swamp, and Plains combined. Over in Legacy, the format has not been overtly oppressed by Wrenn & Six, but the versatility of the planeswalker was homogenizing too many decks into "good stuff" strategies that no longer needed to worry about mana.
Now, both Standard and Legacy are in for dramatic changes. Wizards of the Coast announced today that Standard would be receiving an incredible three bannings all at once, and every single card is in the green portion of Magic: The Gathering's color pie: Oko, Thief of Crowns, Veil of Summer, and Once Upon a Time are all banned from Standard. According to Wizards of the Coast designer Ian Duke, green's dominance was too unhealthy for Standard, and Oko, Thief of Crowns was obviously much too powerful for Standard. Once Upon a Time provided too much consistency for green decks, while Veil of Summer was too good against the cards that naturally kept green in check, necessitating a ban. As fans had called for virtually all of these cards to be removed from the format, it's likely Wizards of the Coast's decision will be received quite happily by players.
The biggest and most unexpected change, however, is the one that's coming to Legacy: Wrenn & Six has been banned too. The planeswalker was a huge reason why Temur Delver decks were so dominant in the format, with that deck maintaining a staggering 56% win rate against the field. In a format as diverse as Legacy, that's obviously problematic. With Wrenn & Six no longer oppressing which strategies are viable in the format, decks using cards like Mother of Runes and Young Pyromancer can once again come back into the fold, hopefully making the format a little more diverse once more.
Wizards of the Coast also made a few changes to other formats. In Brawl, Oko, Thief of Crowns has been banned in tabletop to mirror his previous banning on Arena-only; and in Vintage, Narset, Parter of Veils has been restricted to one, another major change that proponents of that format have been clamoring for for quite some time.
All of these bannings and restrictions are, at least according to the majority of the playerbase, absolutely needed for their respective formats' health. It shows that Wizards of the Coast is listening to its playerbase and, in the case of Oko, is willing to ban cards that were a huge part of the marketing for its most recent set if it means players enjoy Standard again. That's a healthy change and, hopefully moving forward, play design and card decisions will be reined in a little to prevent needing such huge swaths of bans in such a short period of time.
Source: Wizards of the Coast