The newly introduced Model interface overlaps with Graph to a large extent. In addition, feedback on the dev mailinglist has shown a preference by some for a decorator/utility class approach as opposed to the current rich interface.
See development group discussion at https://groups.google.com/d/topic/sesame-devel/CGFDn7mESLg/discussion
Advantages of current object-oriented approach:
implementation-dependent optimizations are supported.
object-oriented approach facilitates ease of use in scripting languages.
Advantage of a decorator/util approach:
base API is less complex, making third party reimplementation easier.