Class of an annotation body

In the OA data model, there is no general RDF Class defined for the body.  But that doesn't mean that the body cannot have an RDF class, for certain types of annotations.  For example, for  a tag, the body has class oa:Tag and for a semantic tag, oa:SemanticTag.   (Those are the only two I can think of from the model, maybe there are others I missed.)
There is at least one use case that calls for a structured body and thus an RDF Class (Structured Review:  http://www.w3.org/TR/dpub-annotation-uc/#comment-on-publication-title).   And it also seems that there is a certain amount of hand-waving that suggests that bodies are going to need to be structured in many cases but I don't think we have had direct discussion of this.
I am in the process of developing a use case along these lines and would like opinions on whether this approach is seen to be legitimate or frowned upon - annotations where the body has properties - because there was discussion of this in BIBFRAME and it seemed to cause controversy.
Ray