LonghornIssues: *Dependencies* were the problem. .NET Framework 2.0 could not stabilize because WinFS and SQLCLR were pulling it in two different directions and WPF was pulling it a third. Each time something changed it broke all the user scenarios built on top of WPF. It pushed out the release schedule for VS 2005, SQL Server 2005, Exchange 2007 (which was supposed to have a SQL Server back end - still doesn't in 2013), Windows 'Longhorn' (client and server). Eventually Jim Allchin cried 'enough' and WPF was pulled from .NET 2.0, WinFS was killed, and Windows Vista rebooted to not use any managed code.
It's very clear that Windows Runtime is such a minimal API because they have tried to avoid this problem: the runtime's feature set was locked about three years ago, so that apps could be built on it without the shifting-sands problem. Lack of updates to the in-box Windows Store apps are likely to be because the runtime is now in flux again for the next release, and the app teams are now working toward their next releases on top of that, not on Windows Runtime 1.0. You'll still notice many areas of Windows 8 where you get booted out of the 'modern' environment into the desktop, even for some apparently straightforward configuration tasks. Why? Because there wasn't enough time to do that on top of Windows Runtime as well as everything else.
