Ansem's research was one thing, but Mickey made him see the error of his ways. Then Xehanort came along and took up the experiments again with something much worse in mind.
When you're stuck in a rut, there's no need to reinvent the wheel. Changing a few simple ingredients will keep the same old dishes from getting dull.
Secession is a given right to be exercised by individual states or singular people of power. What they do with it is another story.