I spent some time porting over 22 of the 35 examples that come with the nice graphical programming environment NodeBox to SuperCollider. (NodeBox is based on Python and specialises in generative graphics.)
If one compares the code for these examples, I think it is obvious how capable SuperCollider is for 2D graphics. It's just as simple as NodeBox and Processing!
Well, some more advanced features are missing at the moment - like reading back paths, image manipulation, bindings to CoreImage, PDF export etc, but simple interactive 2D and animation SuperCollider can handle.
All the ported code lives here...
and also attached as scd.