Redundant RDF datatype classes?

[patrickwestphal]

In the lib/rdf/rdf_datatype/ directory there are the following classes defined:

«abstract» RdfDatatype
getUri() unparse() parse()

BaseDatatype (extends RdfDatatype)
getUri() unparse(value) parse(str) toString()

RdfDatatypeBase (extends RdfDatatype)
getUri()

RdfDatatypeLabel (extends RdfDatatypeBase)
parse(str) unparse(val)

For me it seems like either RdfDatatypeBase and RdfDatatypeLabel or BaseDatatype is needed. Is there a reason for having all of them?
Moreover I'm wondering if we really need this class hierachy here, since it (IMHO) only complicates things unnecessarily.