Valve are continuing to support as many devices as possible with a new Steam client beta now available.
Since there's no gamepad to rule them all, it makes sense for Valve to support as many as they can. Even though I love the Steam Controller, I do understand that it's not going to be a good fit for everyone. Now, Steam will support the PowerA wired/wireless GameCube Style controllers, PowerA Enhanced Wireless Controller and the PDP Faceoff Wired Pro Controller to boost their already rather large list of supported devices.
If they do ever roll out another Steam Machine, being able to plug in practically any gamepad and have it be picked up is a nice selling point too.
Additionally, for those using Big Picture Mode, the Steam community header will now be hidden when using the Steam Chat system to give you some more space. They still need to refine it some more though, since the current implementation isn't ideal.