It conflicts with the common sense of most professional artists and engineers to give away freely the source that underlies their work. The foundation of any business that depends on intellectual property is that people who develop copyrightable or patent-able material carefully protect their creations either legally or by maintaining trade secrets. Money is typically made in these businesses through planned obsolescence.
Growth is achieved through the re-licensing of products as new versions render the old obsolete.
Open source proponents prefer licenses that provide freedom from obsolescence and eliminate dependency on the original owner of intellectual property. The value of open source licensing is the guarantee of freedom that it provides. No open source product need ever become obsolete because the product's source serves as the foundation upon which future derived works are created, and everyone is free to use the source to derive new works. If you play by the rules of true open source, you never have to pay license fees for rights to intellectual property. Open source is not public domain.