Broithe, I don't think that a journey planner that was produced by a body with the resources, financial, personnel and data, of the NTA which excludes the rail option for a journey from Dublin to Cork can be fairly be described as having 'teething problems'. If the journey planner had been produced by an individual or a small private company, without the access to the various transport companies that the NTA have, then I would entirely agree with you.
I have, by the way, already voice my views to the NTA using their feedback form. Let's see what they have to say.