The problem with public todo-lists is that some people read them as set in stone. The same people will start to complain why this feature or that bug isnt fixed or has gotten the attention it needs. ToDo-lists is a great tool for a person or a little team, but making them public is a timewaster and can even make people angry.
Some of the bigger teams fake this, they usually make a todo-list based on what they HAVE done. Then nobody can complain, the preassure is of, and the users feel they get some inside information