All the “Linux” distributions are actually versions of the GNU system with Linux as the kernel. The purpose of the term “GNU/Linux” is to communicate this point. To develop one new distribution and call that alone “GNU/Linux” would obscure the point we want to make.
As for developing a distribution of GNU/Linux, we already did this once, when we funded the early development of Debian GNU/Linux. To do it again now does not seem useful; it would be a lot of work, and unless the new distribution had substantial practical advantages over other distributions, it would serve no purpose.
Instead we help the developers of 100% free GNU/Linux distributions, such as gNewSense and Ututo.