Earth lacks opponent creature weakening.
I have come up with a great idea for an earth card, that would help with this. Just creating the art now!
Perhaps something that slowly converts a hostile creature's attack into the creature's HP (like turning into stone)? Think of it as reverse-accelerate =9
I think there is already a card in progress that turns creatures into lands (consistent with Earthquake).
I don't think Earth really needs a direct means of creature control... Earth elementals are quite tough enough. In fact, what I do when bored is to take my 60-card Earth-Gravity deck against AI3s to try and break my own record of making the biggest creature possible (Armegio + Accelerate + Basilisk Blood + Chimera). Earth is so good at defence that I can pretty much shrug off any AI3 attacks with absolute impunity (and usually still have 100+ HP left when AI3 decks out). I haven't managed to get a creature bigger than 90/90 yet, by the way. But the 90 damage hit sure produces an awesome sound =9
What I'd like to see is something that plays on Earth + Water = Plant. The defensive capability of Earth + Water is nothing to joke about, and the possibility of actually doing serious damage via Life will make both underused elements a lot more popular.