The Software Freedoms [0] don't mean you get to scarper off with other people's hard work. They mean that, once you have paid and received permission to use the work, you shouldn't be restricted in your use of the work.
Software is a thing that we use to get work done, a thing that doesn't necessarily work correctly or sufficiently or whatever other reason you might want to change it. We have a need to protect the rights of users because, without said rights, the user could potentially end up in a situation where their livelihood is significantly impacted by the failing software.
A work of art, on the other hand, is meant for consumption. You can't make a photo so integral to your workflow that replacing it with another photo could be detrimental to your self. Most programs are not reasonable substitutes for each other. Most photos of bumblebees are--more or less--perfectly acceptable substitutes, not because all photographers are equivalent and interchangeable, but because your need to have that photo is not more important than the photographer's need to eat.
The Software Freedoms are not about copyright. Copyright is just the mechanism through which the GPL operates, in an ideology that believes that software should not be copyrightable. It's the belief that these two things are so fundamentally different, that copyright is not the appropriate means to protect software developers, that led to the creation of the GPL. The GPL is nothing more than a hack on top of the copyright system to make copyright--for software--useless. It is not an overall indictment of copyright.