Valve's Steam controller is apparently looking less like a crazy experiment and more like a typical gamepad in a newly-surfaced image.
As discovered by Steam Database, the design shows an analog thumbstick on the left side, which would replace the directional buttons on Valve's previous design. If the image is legit, the controller would have a pair of round, circular touchpads on either side, though, so Valve wouldn't totally be backing off its original vision.
Having tried the original Steam Controller prototype at CES in January, I can understand why Valve would make the change.
With something like a first-person shooter, the right touchpad still makes sense as a way to turn and aim, as it kind of feels like moving a mouse on a gaming PC. Compared to a thumbstick, the touchpad allows for more precise aiming--at least in theory.
But for movement, you don't need precision as much as you need quick action. A thumbstick, much like keyboard controls on a PC, can be quickly thrown in any direction with minimal effort. It doesn't really matter that the controls aren't as fine-grained as a mouse or trackpad.
Still, Valve would be making a trade-off: The thumbstick would come in place of directional buttons, which are popular for fighting games and can be useful for old-school platformers.
Valve could have just ditched the left touchpad entirely, but I'm guessing the company would want to keep it around for games that are mainly controlled by cursor, such as strategy games. That way, users could move the cursor with their left thumbs and use their right hands for buttons and triggers.
Besides, if you're really bothered by the lack of a d-pad and thumbsticks, there are always more traditional controllers instead.
MORE: The History of Video Game Consoles