Casey’s Blog is a great read (also, I’m really looking forward to The Witness).
He basically nails the state of the Windows input APIs (and a lot of other ones) here. I don’t want to publically skewer anyone, but let’s just say that marrying rent-seeking behavior (e.g., need for promotion by adding visible features) and territorialism (the need to protect your turf, especially when your stuff is poorly designed) don’t mix very well. Microsoft’s internal politics amplifies the bad. I’d love to see an official response to Casey’s issue.