Pessimistic answer: Ever seen that joke graphic with the org charts of various tech companies, where Microsoft's is a bunch of nodes with little hands sticking

Pessimistic answer: Ever seen that joke graphic with the org charts of various tech companies, where Microsoft's is a bunch of nodes with little hands sticking out and pointing guns at each other? WPF was a product of the .NET team. WinRT was owned by the Windows team. The two have had a rivalry that's famous for producing collateral damage. Optimistic answer: WinRT was designed to be consumable from many languages and platforms, not just .NET. They preserved as much as they could (e.g., xaml), but you can't rewrite the core of a thing without a few growing pains.