Add the ability to work with a workflow as code in the VS IDE...

Or - have the ability to write code in C# / VB and have it compile into a workflow which can be run in workflow foundation.

Many people write programs in c# and VB, doesn't it make sense that an entire workflow should be able to be written in one of those languages? XAML is a hard language to write a workflow in as it is very verbose when coding, and the visual designer can be much more difficult to work with than a textual language.