It’s tough to “aim” the After Effects SDK; it could be used for so many different things.
One could learn the rudiments of C or C++ based image processing, just fiddling around with the samples. One could learn about workflow automation just reading through the headers (AE_GeneralPlug.h would make most integration engineers’ mouths water).
The SDK Guide could be a reference manual, a cookbook, a tutorial…
What do YOU hope to get out of the next After Effects SDK? Besides the XCode and .NET 2005 samples, I mean?