I disagree. The Constitution is very easily understood. It was written in plain language and is very straightforward on what the government is allowed to do. It's when some legislator decides to try to pass it by the people that the meanings get obfuscated. They try to stretch the meaning of the interstate commerce clause to the breaking point. Or they try to mealy mouth the 2nd Amendment to mean a collective right, or the claim the general welfare clause (which is not a clause that means anything other than a general introduction to the powers of congress) to mean free money, food, education, medical care, etc.
Since the population was not as educated then as it is today...
Here I have to disagree as well. People knew grammer and what sentence structure meant and how it was used to delineate an introduction clause from the specifics, or that the first part of the 2nd Amendment was not a limiting clause. It seems that just in the last century that people were dumbed down to the point where those things started to mean nothing to the people.
It does not take a scholar to understand the Constitution. It was written for the people to understand. If it had been hard to understand, it would have been even harder to ratify than it was.
The majority of people outside the cities in our early day could neither read nor write. The New England states were an exception perhaps. As far as the illiterate being able to understand the constitution goes- well, it is a nice sweet myth. You can believe if you like but it is totally false. Only after the spread of public education was literacy widespread.