You're comparing interactive art to painting, which is a flawed analogy. This isn't about cheap, or free, and it's only cursory about freedom. It's about that in order to curate digital history, you have to be able to redistribute it, and to be able to keep the software running.
I agree that it is not the best comparison. It is the best I could come up with... The problem might be that I compared out of context - a texture is not very different from a painting (in theory, physical anomalies aside) - I did not intent to compare paintings to complete games. However, the interactivity results from the combination of the textures ("static part", somewhat comparable to paintings) with the code (making the textures interactive, animating them etc.). So I would come to the conclusion that the interactive part has been shared freely.
