They started from a white piece of paper for Windows Phone 7 , so it just simple can't be done to leapfrog other platform. Because a lot of the API's build on the underlying platform. They choose to get the 90% case as perfect as possible and ship that.
Then with the power of Silverlight and XNA I'm pretty sure if the basis is stable they can easily leapfrog ahead of competition. XNA and Silverlight alow rapid development, in contract to objective C and C++ / Java the other platform are build on.
Give them some slack? Why? They've had all the slack they could have asked for. They've had years to look at what the competition was doing and where they were dropping the ball, and subsequently act upon it. This whole "Doing the bare minimum is good enough
because it's a 1.0 release" mentality is horribly frustrating.
As for the platform, the fact that there aren't even any pivot or panorama controls - staples of the metro experience - is just pathetic. Why does this have to come down to some hobbyist on codeplex instead of just offering a native, supported control that's
100% consistent with the ones in the built-in apps? They hammer upon the greatness of the metro experience and then don't even provide people with the tools to actually create applications with a consistent UX? Inexcusable. So much for a great development