Are you suggesting that the session token should actually store session data?
As an alternative SessionManager, it appears to have some advatanges that others do not. It is the only option (AFAIK) that avoids the session hijacking problem without relying on security-through-obscurity (the problem you mentioned, but its not one that gets me excited). Its also the only sensible option that lets you bookmark your place in a session, and return to it much later (which interests me more).
Or are you just pointing out the difference between the implementation an implementation that meets the requirements of sessions and an implementation adequate for things like the tree tag?
Isnt the tree tag an example of one Session use case? It smells alot like a session to me.