There are questions about the Nostradamus prophesies and why some things were never predicted. Maybe those things were not as important to the history of the world as you may think. You may think that something is a major factor in your life, but in the grand scheme of things, it may mean nothing.
Also, it is questioned why we don’t use his predictions to prevent the future. If we prevent the future, then his collection of predictions would just be a collection of fictitious stories that never really happened.
It is a thought that you can’t change history, and if you could take a time machine, back in time, any changes that you would have made, would become the new history and you would never know that the previous history had ever occurred.