Just because the Founders ratified a Constitution as they understood it does not mean that we ratify one with the same meaning. We ratify our Constitution, as we understand it, or not. We cannot justly be bound by others' choices.
Consider the Constitution as might a philosopher of language, asking, "Is the preamble's claim about ordaining and establishing the Constitution true?" The easy answer is, "Yes, it was made true by the ratification of at least nine state conventions." That looks like as near a truism as history can offer. But does that same preamble hold true today? The answer depends on whether we the present people ordain and establish the Constitution.
Suppose, by way of thought experiment, that a meteorite struck the nascent U.S., wiping it out but leaving documentary evidence, such as the Constitution, abroad. An Englishman reading that Constitution after the disaster would observe, "Yes, they did ordain and establish that Constitution. But it nowhere survives, today. The Constitution died in that huge gaping crater that was once the United States. Taken in the present-tense, the Constitution lies. We can understand it only as a historical artifact." Less dramatically, the same would hold true if everybody in the U.S. suddenly decided that it just wasn't worth the trouble, and magically gave up the collective hallucination of a federal government. Unless we keep it alive with our consent, the Constitution means nothing more than an account of what once was.
The choice boils down to this: If you rely solely on original meaning, you will ordain and establish a Constitution that was. If you want to ordain and establish the Constitution for we, the living People, you have read it through living eyes.