When the Charmed Ones and the next generation heard about the coming of a new power they were not too worried.
Powers came and fell quite frequently in the magical world and they were confident that if this new power proved to be a threat they would be able to handle it. They had done so time and time again.
So they decided to ignore it until this power showed itself and they went on trying to have their normal lives outside of magic.
Perhaps things would have been different if they had decided to look for the new rising power.
Edited: July 13th, 2010