People say this about all unjustifiable products. "Why do I want a Juicero? Why do I need a Surface Laptop?" The same form factor, just works, convenience argument.

Nobody wants to acknowledge that it's all marketing halo. It takes less time to install SteamOS on the PC that you already own than it takes to buy and unbox a Steam Machine. But that's not "oooh new thing" retail therapy, so everyone waits with bated breath to see if they can afford the media center equivalent of jewellry. Nobody actually cares about functionality, convenience, or form factor if they're ignoring the most functional, convenient and proximate solution.

Somehow “it just works” is a meme or joke for every company except Valve

Yes, I wasn't criticising just saying a large company who will also be taking a 30% rake on most software run on it is not passing on any bulk purchasing discounts. For some it will be well work the convenience, for me it is not (but the Deck was).