I would like to see something similar such as WriteableBitmapEx in the Nokia Imaging SDK. I ended up using it in my own example application, since it made the code so much more readable. The WritableBitmapEx is really a wonderful library for manipulating bitmaps. I could have implemented my own bitmap scaling algorithms, and then draw on top of the canvas, but that would have complicated the code a lot, while I wanted to keep it simple.
I see WriteableBitmapEx and the Nokia Imaging SDK as complementary offerings. It's fairly easy right now to create a bitmap using the WriteableBitmapEx, then feed the resulting bitmap into the Nokia Imaging SDK for further processing. The WriteableBitmapEx does a wonderful job, I would not expect the SDK to replace it. Perhaps some helper functions could be provided to ease the interaction between both libraries?