Wooglet's was buffed because AP champs couldn't compete with AD bursiers/caster w/e you want to call them. AP champs couldn't compete with them because S3 brought huge changes that made life extremely easy for AD champs: armor is more expensive, mixing flat and percentage ArP is more effective, and they got Black Cleaver to really emphasize the power difference.
In response, Deathcap's Dominion replacement, Wooglet's Witchcap, was buffed to be easier to build into, it also has Deathcap's famous AP boosting passive as well as Zhonya's famous 2sec stasis active. Wooglet's was turned into Zhonya's Ring, an item that was long removed from the game because it offered a massive power swing against melee AD champs in just one item.
Wooglet's Witchcap is an OP item. A mage before and after this item is like night and day, it's like the difference between being armed with a pellet gun and being armed with a deagle. Wooglet's offers the largest offensive power boost for AP champs while also offering the most significant defensive power boost for squishy champs. It's OP; and there's really not much more to say on that matter.
Is it bad that it's OP though? Is it Wooglet's fault that it's OP? Is it the fault of AP champs that they need an OP item to compete against the Black Cleaver crowd? The truth of the matter is that AP champs can't survive in this game mode without being able to build one item and suddenly go super saiyan. Without Wooglet's, mages are fodder for AD champs.
So that means Black Cleaver is OP, right? Yes and no. Stand alone, Black Cleaver is a balanced item. The problem with Black Cleaver is that it makes the now more expensive armor stat even more expensive, for a whole team, by allowing AD champs to apply the armor shred debuff, in an AoE, with their abilities. So in a game mode like Dominion, seeing a champ with physical AoE damage build a Black Cleaver is the same as knowing that you'll have 25% less armor as soon as a fight breaks out.
How do you counter AD when armor is a bad counter to AD? You need the stasis active from Zhonya's to outright stop the incoming damage. Zhonya's would be really expensive to rush, how do you keep your damage competitive? You need the raw power boost from Deathcap. How do I afford over 6k gold worth of items by the time someone has dropped half that amount to pick up a Black Cleaver? Well, that's how you end up with Wooglet's.
If every AD champ is running around with an item that provides durability, damage, and more damage via defense shred for only 3k gold, then every mage needs an item that provides durability, damage, and more damage via a raw AP boost passive for only 3(.5)k gold to stay competitive.
How do you stay competitive in Dom if you're playing a champ who doesn't build either of these items? Well, unless you're a tank, you don't.
tl;dr: The whole situation is buried up to its neck in "completely f*cked", but if you must play Dom in the meantime, pick a champ who rushes either of these items.