so if "no self-publishing until a year after launch" is true, I'd wager that the reason they're doing that is because they don't want to have to worry about sending pre-launch, relatively unoptimized dev kits to people, and spend time having to support and maintain that for a bunch of smaller companies and developers. For launch, they seem to be primarily focused on the AAA heavy hitters, and/or established publishers, which are a bit of a known quantity.
Instead, they'll wait for the "anyone can use their PC and retail Xbox to publish full games" stuff and then anyone can do whatever, since the infrastructure would be in place at that point.
Sony took the opposite approach of going ahead and sending out early devkits to indie devs and building that relationship up front.
Sony's approach gets the benefit of lots of indie support early on, and the messaging that comes along with that, at the cost of losing the random coder in their bedroom who wants to make a PS4 game. Random bedroom coder could theoretically still get a PS4 devkit, but they'd probably have to have something a bit more polished to show for themselves first. They couldn't just email Sony and say "hey, I want to put my massage app up, send me a devkit, kthx"
Microsoft's approach gets the benefit of pretty much anyone with a PC and an Xbox One being able to release whatever game they want, dumb or not, without having to get any approval at all (beyond the basic "it doesn't crash when you first boot the game" testing). The drawback is that this system won't be fully ready until a year after launch, so they'll have to take the PR beating in the meantime, and also potentially lose indie mindshare.
As I mentioned before, this is a possible reason for the 5GB/3GB RAM split. If they reserved too much for games, then there wouldn't be enough leftover for the "devkit environment", which usually takes a lot of extra RAM. Since they've mentioned today that they "designed the system from the beginning to eventually support this", that seems like the most plausible reason for why so much "non-gaming" RAM is reserved.