NASA’s Blue Marble series was inspired by the whole-Earth image taken by Apollo 17 in 1972, but aside from that, I haven’t heard much about why it was revived as a series in 2002. Well, Quartz has the backstory:
[Robert] Simmon and his colleague at NASA at the time, Reto Stöckli, created the iconic image that ended up on the iPhone in part to undercut what he saw as undeserving operators profiting in the marketplace for space imagery, he told Quartz. At the time, he recalled, similar falsely colored images rendered from older black-and-white NASA data were selling for up to $10,000. Simmon and Stöckli’s image, as a work created by US government employees, was in the public domain—free for anyone to use, for any purpose, without restriction. Simmon posted it on the NASA website and didn’t think much more of it.