As great as our Constitution is, it was written and adopted some 223 years ago, a time when those living had no idea what the future would hold. It is my belief and the belief of many others, that if the writers of the Constitution were to draft the document today, it would not resemble the 1787 version, not exactly.
No one will ever know for sure; but I am of the belief that our forefathers would not tolerate the cries of "kill the blacks" or "kill the Jews" or anything along those lines, and would have written laws to prevent citizens of this Country from living in fear of persecution.
You're right. If the Constitution was written today, by the same kind of people who wrote it 223 years ago, it would reflect today's culture instead of theirs and would include all the components of subsequent amendments that still stand. There would probably be some additional components to prevent the corruption of the document as has occured in the liberal courts and via interpretation of others on the Left.
Otherwise I think those same visionary people would leave the principles embodied in the Constitution exactly as they are because they have been proved to work everywhere they have been tried.
They would keep the Constitution as a document to secure our rights, and to prevent the federal government from otherwise interfering with us forming the society in which we wish to live.