AndyC: It doesn't have to be. If you stop worrying about themeing and the more 'advanced' aspects of WPF you can knock out a quick interface in next to no time.
Oh so the only cost-effective apps are Northwind demo apps! I see! Thanks.
Even dumping theming (which we haven't touched in over a year), using code behind, kicking MVVM to the curb, WPF is no cheap framework to code against. We all know building a ball of mud in any framework, language, etc. is still just a ball of mud. You can't say the cost of building a WPF ball of mud app is equal to the cost of a Winforms well architected app.
Microsoft may continue to listen to those that pretend that it all comes down to choices with WPF but in reality it comes down to people making choices one which development platform to use -- including Microsoft's competitors. Add that to the fact that there are quickly more client platforms to build apps for other than Windows (Android, iOS) and it should be obvious that Microsoft needs to adjust its strategy here.
It is so tiring hearing that same old academic argument of "your holding it wrong".