It is not that simple. It is not that Prince Albert says "change it" and it is changed. The only fact that this tiny little dot in the South of France still is an independent state is directly connected with the position of the family ruling it for more than 700 years.
Besides the fact that the monegasques themselves have to agree in a change of the Constitution, there are three succesive treaties between France and Monaco, apart from other international treaties as the famous one of Vienna 1815. The changes in the Constitution of 2002 regarding the succession had to be approved by France. The interest of France is that Monaco extincts as a protectorate and becomes integral French territory when the succession is not exactly executed as agreed between the two countries. I can imagine that, after just a decade of a renewed Constitution, the Prince and the Government are not willing to open Pandora's Box once again.