Aggro's trumps - cards like Sulfuric Vortex, Ankh of Mishra, Winter Orb, and so on - are both cheaper to cast than control's trumps and beat them in a head-to-head clash, and it's much easier to get a nut draw with aggro than with control.
Vince, when I watch MTGO cube matches, very often the control player is simply doing nothing in the opening turns and hoping the aggro deck stumbles along the way, which seems pretty boring and non-interactive. Then they hope to win the game by just running out a Thragtusk or whatever.
In my own cube, cards like Augur of Bolas and Sea Gate Oracle give control decks a way to interact early and make the match-ups more dynamic. Have you experienced any of these problems? For me, I really like games like Legacy where the interaction and positioning starts on Turn 1, as opposed the types of games I see in the MTGO cube. I would rather have more of the early plays and less-dominant late-game bombs (e.g. no Wurmcoil).