And that is why controllers aren't sexy. Their actual controlling powers require a lot of thought to use properly, which most people just aren't good at, and actually proving that you're using them properly involves the right situation to be assumed and quite a bit of math.
Actually, this is a lot of misconception about what control is. Winged Horde is not a real example of a controlling power. It's an example of a debuff power.
Some people think of debuff as control, but it doesn't really control. The monsters still get in attacks and they can still make reasonable decisions and hork the party over big time. Yes, the monsters do less average damage to the party, but one doesn't really think of a Leader as a Controller when a Leader debuffs foes.
Real control is restricting movement or restricting actions. Winged Horde does neither of these unless it actually gets lucky and kills a foe (in which case, that foe's actions and movement are totally restricted).
WotC doesn't actually provide a lot of good controlling At Will powers for controllers.
Take Storm Pillar for example. On the surface, it sounds like it does a lot of control. But in reality, it at most influences foes. The foes actually can still make decisions to pay the price and move through it or can even do ranged attacks while next to or under it. It may or may not actually control anything. A monster with Resist Lightning 10 or 15, it doesn't even influence the monster at all.
Some people call these types of powers "Soft Control". Soft Control is no different than any other power in the game system. Even a Ranger who is just doing damage is doing a limited form of Soft Control. He influences foes by having them attempt to gain cover, or attack the Ranger, or however he influences them. But influence is not real control. Nearly every attack power in the game system influences foes both mechanically and non-mechanically. A Fighter using a Mark is doing Soft Control, but this is more than just influence. It is also game mechanics.
Every single class in the game system has examples of Soft Control.
Hard Control powers are things like Walls, Slow, Restrain, Immobilize, Daze, and Stun. They actually game mechanics-wise prevent the foes from doing things. These are examples of real control and controllers get very few of these as At Will powers.
But these are the true strength of Controllers. Every PC does Soft Control in one way or another, not just Controllers. Hard Control is the key to a good Controller really handling an encounter and Winged Horde does not do Hard Control.
Hence, touting Winged Horde's Soft Control aspects as making it superior to other At Will powers which do a different type of Soft Control is subjective. A Wizard throwing out Scorching Burst is still doing Soft Control. For example, he is influencing foes to not stand around in groups where he can blast them, hence, restricting the actions of the monsters and giving PCs more opportunities to flank monsters. The monsters can ignore the Wizard and stand around in groups, but then he just blasts them again. And of course, the Defender and the Wizard can easily work together to blast foes regardless of what they do. For example the Wizard can delay to go after the Defender, and the Defender shifts back a square at the end of his turn in order to expose multiple monsters to a Wizard area effect attack.
I cannot count the number of encounters that I have seen where the DM spreads out the foes so that they won't get caught in area effect spells. This is soft control. The monsters are self restricting their own movement. This allows the PCs to focus fire on the outlier monsters more easily without the monsters being able to easily get flank in return. The DM spreads the monsters out, the PCs pick them off one by one. Just by having Scorching Burst, or Thunderwave, or Nightmare Eruption in his repetoire and using it, the Wizard PC is influencing the NPCs to do certain actions and is exerting Soft Control, just like the Cleric is doing Soft Control when he debuffs a monster. It's just different types of Soft Control.