Great points... what some people want is to "have your cake and eat it too".. no expensive proprietary hardware (or worse, inability to upgrade), or having to choose between the two platform variants (roku vs walled garden boxes)
I know that we don't have the kind of resources right now that are needed to get this up and done, but it's just so within reach.... the chinese clone phones to use as a remote are readily available (though they need an external case of some sort for durability), hardware could be standardized (a slim and a "fat" model), nice looking cases are most likely available...
So i think if we manage to get the software side taken care of (a monumental task though), the hardware will be much much easier to come by.
I don't have any illusions about this project, but i think that the walled garden companies will not readily bridge the gap between their own offerings and roku's for at least a few years... which creates that nice niche for a truly "free" ecosystem, one that webOS can fill..
It's really worth laying the foundation for something like this, because who knows, a homebrew kit might appeal to a few thousand people, and if there will be enough momentum, a reputable chinese manufacturer may become interested in selling it as a packaged, ready-made product. This isn't like a mobile phone, and much more realistic IMHO, because there is a market for unsubsidized boxes and independent content, and we aren't really aiming big. If we start with small steps and the market's current offerings don't change, like you said, we could really have something. I'm not saying it won't be hard, i'm just thinking this is less risk and potentially "cooler" than trying to re-enter the phone market right away. A foothold in consumer appliances isn't bad at all.