Some people may be wondering, "What's the big deal? Why does it matter if software is licensed instead of sold?" The main reason it makes a difference is because of some of the technical details of copyright law. In order to use a computer program, you necessarily must make one or more copies of the software. Some examples: copies are made on the hard drive, copies are made in RAM, and copies may be temporarily made in caches and other places. Normally, copyright law would supposedly prohibit you from making these additional copies. Only the copyright owner, in this case the software publisher, is allowed to make copies.
At some point, Congress decided that copyright law needed to make an explicit exception for computer software. So section 117 was added to U.S. copyright law. This section recognizes the fact that computers can't make use of software without making these incidental copies. As such, the section permits these copies to be made as long as the copies are necessary in order for the software to work on a computer.
But there's a catch. According to section 117, only the "owner" of a particular copy of software is permitted to make these incidental copies. In other words only the owner of a copy of software is allowed to actually use the software on a computer. This is where "licensed, not sold" comes from.
If we subscribe to the view that software is licensed, not sold, then the software publisher is still the owner of any copies of the software. End-users do not own any copies, even those copies that the end-users may have in their possession. So, under copyright law -- even with section 117 -- end-users have no right to actually use copies of software on computers. Instead, the software publisher gives end-users permission to use the software and to make certain copies. The EULA is the agreement that grants this permission. In order to accept the permission given to use the software, the end-user must accept all other terms laid out in the EULA, many of which typically restrict the users' rights far beyond what copyright law would otherwise allow.
If, on the other hand, we subscribe to the view that software is sold, not licensed, then the end-user takes ownership of any copies of software that they buy. As such, end-users are then free to use the software without the publisher's permission. Section 117 allows the end-user, as the owner of the copy, to make any copies necessary in order to allow the software to be used on a computer. Hence the end-user does not need permission from the software publisher to use the software and there is no need for the end-user to agree to an EULA. When software is sold, end-users are afforded all the rights that copyright law provides.
This brings me to one of the most bothersome consequences of the practice of "licensing" software instead of selling it. The use of EULAs has become so widespread, so ubiquitous, that virtually all commercial computer software produced today is supposedly bound by an EULA. If we accept the assertion that EULAs are valid and that the software is indeed licensed and not sold, then section 117 of U.S. copyright law has been rendered meaningless. There would be virtually not a single copy of software that would be affected by section 117 because virtually all copies of software would be owned by their respective copyright owners. Section 117 only has meaning when there are copies of software that are owned by people other than the copyright owners. In other words, software publishers are attempting to unilaterally reverse a law that Congress created for the express purpose of allowing end-users to use software created by others. And that just makes me angry. It should make the courts and Congress angry too.