Michael, what Collada adds that OBJ doesn't support is scene hierarchy so we can keep the relational information of parent-child relationships. Granted this may only be a necessary thing once you implement such a thing with a scene manager.

Also, Collada is gaining support and is an 'open' standard and not owned by any one entity unlike extortionist-Autodesk. I can't say I'd expect FBX to be too open now that they are tailoring it for Maya & Max interoperability.