I’m not sure how a published work from 1615 (re: Don Quixote) doesn’t count as “commentary.”

But since you seem to want a clearer opinion of the people who actually initiated copyright in the United States, I give you the correspondence of Thomas Jefferson and James Madison. In it you can see that Jefferson was opposed to such monopolies while Madison couldn’t foresee the the abuses that would come about.

Luckily, others have already done the work for us:

http://onlinebooks.library.upenn.edu/webbin/bparchive?year=1999&post=1999-02-11$2

Thomas Jefferson:

The saying there shall be no monopolies lessens the incitements to ingenuity, which is spurred on by the hope of a monopoly for a limited time, as of 14 years; but the benefit even of limited monopolies is too doubtful to be opposed to that of their general suppression.

Here we see a limit on government granted monopolies which was applied to patents to 14 years. This matches what the law had been at the time.

If you read the article I’ve linked, you can see that Jefferson felt that protection of the people from monopolies was so important, that it be included into the Bill of Rights along with “…freedom of religion, freedom of the press, protection against standing armies, restriction against monopolies, the eternal and unremitting force of the habeas corpus laws, and trials by jury in all matters of fact triable by the laws of the land…”

Now it’s easy for someone to dismiss this argument since it talks about patents and not copyrights. It wasn’t until 1790 that Congress passed the first copyright law which gave a limited monopoly to creators. Before that it was considered a legal issue for individual States. Copyright protection in the United States was first championed by a group of authors, including Noah Webster and Joel Barlow. (source – Warning: PDF) http://lsolum.typepad.com/copyfutures/files/nachbar_constructing_copyright.pdf

The Copyright Act of 1790 was an altered, rewritten version of England?s 1710 Statute of Anne.
http://en.wikipedia.org/wiki/Statute_of_Anne

Legislation conferring exclusive rights upon the author of books not yet printed or published for a period of 14 years and for a further 14 years if the author was still alive at the end of the first period. The legislation also provided the same rights for the authors or owners of books already in print for a single 21 year term.

As with each extension to Copyright Law in the United States, there was discussion for and against it by representatives in congress and those who would benefit from it the most. This includes the 1909 Act which rewrote Copyright law. A response by the then music industry against player pianos of all things. Then there’s the Renewal Acts of 1962 and 1974 which continued the posthumous copyright extensions and removed the registration requirements. Congress commissioned multiple studies on a general revision of copyright law, culminating in a published report in 1961. A draft of the bill was introduced in both the House and Senate in 1964, but the original version of the Act was revised multiple times between 1964 and 1976.

To try to suppose that none of these changes and extensions to copyright before 1974 were without debate is absurd.