You should probably try an actual steam game with the controller if you're going to test how responsive it is. I play Witcher 3 with the controller and I experience issues where my control scheme won't recognize diagonal inputs on the stick, something that it has no problem doing on Steam games. It could just be that your settings were not quite right and you probably would've benefited by playing an actual steam game with community profiles that have been fine-tuned for the game. I agree that there is a bit of a learning curve with the controller, but after about 5-10 minutes, I still found it multitudes easier to work with than the XBox controller, especially given how seamless the experience can be since you can actually easily use the controller in almost any interface, including desktop.
I am definitely looking forward to the non-steam game improvements, though, and they could definitely afford to focus on making control settings more accessible and ironing out some of the bugs the controller has with certain games. I still think it is a shame, though, that you chose to focus on non-steam games and critiquing controller responsiveness on controller configurations you built in a day. The steam controller is definitely very particular and finicky right now, but it seems you took the least optimal path for the controller to have a chance to shine.