The misuse of IP is often conveyed by comparing the result of an overreaching copyright claim or enforcement to the "original intent" of copyright law.
The so-called "original intent" is often derived from the text of the U.S. constitution, which writes "The Congress shall have Power [. . .] To promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries."
What does this mean? Essentially, that the natural state of being is for there to be free expression. In other words, assume that no copyright exists and that people are free to say, perform, or write whatever they want.
In this state, people have no incentive to produce anything that requires any sort of invested time or money, since they will not receive any guaranteed compensation from it. The result will be a general loss to the public - the loss of the words, music, and art that was never produced.
In order to solve this, the law steps in and slightly limits free speech, free press, and so on, and grants a time-limited monopoly to those who produce something worthwhile, so that they can use that time to make money from the work. In theory, the law limits the public's rights just enough to encourage the creation of the work, and no more. After the copyright has expired, the work passes to the public, which was the entire point to begin with.
Even if this was the original intention of the framers of the U.S. constitution, this is not the only argument for the existence of copyright, nor is this necessarily the only "original" intent of copyright laws.
Copyright laws pre-date the U.S. constitution. Even before the printing press, some books claimed within them the exclusive right to reproduction and warned others about divine curses should they make copies. After the printing press, a whole series of laws, precedents, and international systems were bandied about (such as the Statute of Anne), before the Berne convention essentially became the de facto international standard.
Libertarians argue that intellectual property qua property is a modern invention, but it's really not. It's not that weird to believe that someone "owns" a worthwhile idea, phrase, writing, artwork, or piece of music. It's natural and moral to acknowledge the source of a particular work; claiming to be the originator of an idea or phrase that isn't yours, or neglecting to mention whose it is when you know, strikes most people as morally problematic. Once you acknowledge that something ephemeral has a source, it's not a big leap to believe that they have some rights to its presentation or dissemination.
If this is the case, than claiming that the sole intent of copyright is to benefit the public and not also a moral right of the originator of a work is somewhat disingenuous, regardless of what the U.S. constitution writes.
The problem is one of conflicting rights: namely, the right to free expression (speech, press, and so on) versus the right to possess or control intellectual property. Which right is more important? Can there be a balance? Can there be a win-win for all sides?
According to many philosophers, the only natural rights that all people possess are to life and to liberty. Already you have a conflict. The notion of a right is of something that limits the liberties of others. My right to life is only usefully defined if it includes a duty for all other people to not abrogate that right. All other people must be forcibly constrained from acting in a way that limits or lessens my life.
Other philosophers add a number of other basic rights to this list: the right to property, i.e. that what you hold others cannot summarily take from you, the right to be free from torture, and so on.
Regarding the right to property, the issue here is physical property versus intellectual property. The big difference is that I must be dispossessed of a physical object for someone else to have it. For instance, if I claim a piece of land, the only way someone else can have some of that land is for me to have less of it.
Intellectual property, on the other hand, can be obtained by others with no actual loss to me. I may own how to create a fire, but if others also spread this knowledge, I don't lose this information. It is analogous to the spread of fire itself. I may possess the only torch. If another torch is lit from mine, mine is not diminished.
However, there is a loss involved, even for intellectual property. If I am the unique possessor of a piece of information, it has value in that others must come to me to obtain it. The more the information spreads, the less valuable my property. So loss is incurred by "stealing" and copying my information.
Many would argue that information wants to be free. That, unlike physical objects, or perhaps more like fire, once information exists and begins to spread, any attempt to control it is unnatural. Therefore, I should never have evaluated the holding of this information as having any value to begin with. However, all that this means is that I should have obtained a much larger sum up front for releasing the information to the world at once, rather than expecting to obtain a small amount from each person who wants it.
Supposing that we discard the idea that information wants to be free and that copyright exists only to liberate it from those who would otherwise not release it. Let's, for a moment, agree that people should have a right to own their intellectual works.
This still begs an important problem: all progress we make as humans relies on incremental steps that incorporate all previous human knowledge. Every piece of science, math, art, engineering, and so on is built on every other piece. If all knowledge is locked up with the owner of that knowledge, we may as well just throw in the towel as a species.
Excessively restricting knowledge is detrimental to human progress. It seems to me that there is one more natural right: the right to use ideas to create new ideas.
Limits should be placed on any knowledge ownership, so as to ensure that all works enter the public domain in reasonable time. In addition, more severe limits should be placed on derivatives created from owned works. Otherwise, the human race ends up strangling in a quagmire of IP holdings. Even if IP is a natural right, it is in conflict with a right to use the collected knowledge of our species to grown and contribute back to our species.
Copyright law should still strike a balance between these two rights.