Well, the problem with this is that it would require a change to the firmware in the Hub. Right now the hub is “hard wired” to phone home as soon as it’s plugged in. It isn’t designed to do anything other than communicate directly to the ST cloud and receive it’s instructions from there.
You’d need a new firmware that point to a different location. Further, ST would have to release a lot of info re: how SmartApps function and how everything ties together to allow individuals to install locally. There’s also the support aspect of managing the system on hardware that isn’t theirs. And there’s questions on whether this would be a full time server or only act as back up if the cloud went down (there’s advantages to either way in my opinion).
Of course, none of this is impossible, but it is complicated. It would stretch the resources of a team that I think is already pretty stretched. Beyond that, and perhaps most importantly, I believe that Hub 2.0 is suppose to do everything you listed above. While the price hasn’t been released I think they are aiming for less than $300 (at least).
So I guess it comes down to a question of saving some end users a few hundred bucks but taking on a large development project (new firmware, framework for a local server to operate the ST “os”, method for a local server to download SmartApps), and add new challenges to the support aspect.
In the grand scheme of things I think it would be smarter for ST to just focus on Hub 2.0. The potential lost sales in customers who walk away from ST because of lack of local server support is probably less than the costs incurred by developing and supporting this option.