For the same reason hardcore fighting gamers are almost exclusively using arcade sticks. The layout does not look efficient for "moderate" fighting game players..TO ME.
Is it really that hard to understand?
But it pretty much is more efficient... your thumb is moving across less buttons, and simultaneous presses are made easier. Please tell me: how do you input 1+4 or 2+3 when playing Tekken on a normal controller with just your thumb? It's really fucking hard, but the rear buttons on the steam controller make this a lot easier.
Also, you're now talking about relative effectiveness of a controller for a fighting game. That's a different argument. PS3/360 controllers aren't ideal for fighters, either; they aren't designed to be, nor is this.
So, if your overall statement is, 'this doesn't look that great for fighters'--then yea, you're right, and I agree with you. In terms of layout potential, it's probably better than a 360/PS3 controller, and at worst, exactly the same
because you can fucking map face buttons to the trackpads.