Expression Blend – Flash – Thermo – Go Designers?

Juten Tach,
i currently have the pleasure to work with WPF in an offline Terminal project. I can’t say much about the project itself, but it’s fun and i’m digging into .net development and C# quite a bit. Also i am using Expression Blend 2 for building the UI and Visual Studio Express to code. I’m not going to talk much about differences to Flash, so many people have done that and are doing that. I can say, that i feel, that Expression Blend 2 feels quite buggy sometimes, i often have real graphic errors in the UI of Blend. Also conceptionally, i really miss the possibility to have XAML partial classes being able to be extended. Means, i want to build a control in XAML and want to extend this control in another XAML class. As far as i know, this works in Flex neither.
Anyay, I am a technical developer, but i am currently building the UI completely on my own. Means, i have not done the design, but i am building the UI based on photoshop layouts i got. Working with Blend currently gives me a hard time understanding the concepts of Blend, WPF and .Net. As far as i know until know, you cannot build a nice looking UI, that is at the same time scalable and fits the needs of developers, just by using Blend. The script editor in Blend is very basic, so building classes is no fun at all. But while building the UI, i have to think about classes and how i can build extendable components. I have to make decisions, whether i use templating methods, whether i use class inheritance, how i manage styles and lots of other things, that are solely bound to the UI. While doing that, i ask myself, how would designers be able to do that? Are tools like Blend and Thermo really meant to give the designers the power of building UIs? If so, what kind of designers are supposed to do that? The designers i know have little to no knowledge about coding and application structuring. And I don’t blame them for that, because it has never been their job. But what kind of designers do we really need?
I think, as we see more tools like Blend and Thermo coming up, what we really need are ideas about processes on how to use these tools effectively and what kind of people are involved.