I'm not quite sure about the intent of the original post. Is it an argument to replace the Constitution with something more simple like a decree from the dictator?
Absolutely not! I too think that The Constitution is a great document to organize a country around.
When The Constitution was first adopted, slavery was an institution protected by it. Obviously, one of the great things about the document is a certain amount of flexibility, subject to interpretation, based on when in history the concepts are being applied. Remember, that same great document was the source of the laws that prevented women from having a vote until the 1920's.
Would you care to cite the specific sections that support your thesis?