Chair Yellen made a similar point in her March press conference: More generally, you know, the end of 2016 is a long way out. Monetary policy will be geared to evolving conditions in the economy, and the public does need to understand that as those views evolve, the Committee’s views on policy will likely evolve with them.
And that’s a kind of uncertainty that the Committee wouldn’t want to eliminate completely from its guidance because we want the policy we put in place to be appropriate to the economic conditions that will prevail years down the road.