Well, it's "natural" to program Amiga in C. I mean all the examples from DevCD, for example, are pure C code.
In the eyes of a beginner C++ looks scary (as a novice, I know that

. Lots of complex structures etc, namespaces, constructors, pointers, polymorphism etc. It doesn't look very nice and clean, no wonder since it was originally extended from C.
But the point is that C is an old language missing many features, and C++ is very important language these days (with Java). Maybe this could be taken into account with the new developer material?
Anyway, I hope the best luck to you with your book and I will be buying it when published :-D