Hi,
Thanks for the feedback! Project Cooper is primarily designed for individuals who are not trained in CAD but need an occational drafting program for simple diagraming, sketching, etc. This includes non-professionals who work on small projects (for example home remodels, woodworking etc.) or professionals that are not usually involved in drafting but that may need occational access to a simple layout and drafting tool like Project Cooper.
That said, Project Cooper can be used in many different ways and can certainly be used for simple renderings as you suggest.
You can already import raster images via the 'Insert Picture' button in the Toolbar. You can also open some non-native dwg files in Project Cooper, but the number of files that are supported at this point are very limited. We are working to change that - and will be supporting many more non-native dwg-files (for example from AutoCAD) soon.
Project Cooper is different from Google Layout in that it is primarily meant to stand on it's own, while Layout is mainly a support tools for Google SketchUp.
I hope this helps.
Thanks,
Yan