1. Mom walks into store to buy her child a game system with zero prior knowledge. 2. Mom sees XBox, PS4, and 8 different SteamOS boxes on the shelf. 3. XBox and PS4 get ignored while Mom is trying to figure out which SteamBOX would be the best bang for her buck.
All they need is 1 SteamBox on the shelf that matches the price point of the other consoles and they will win this war in a laugh-er.
Mom has no way of knowing that these things exist and goes with what the television told her is good.
I agree with most of your other points but when it comes to video games parents think of what has been heavily marketed to them or what their kids ask for. I would not buy one of these for a kid either, get them a Wii U or something.