I think it's similar to third wave feminism. It's a revolution that has already won for most practical purposes, but keeps on fighting.
In a world, where almost all software was proprietary, and open source only made sense if you're living in towers of academia - RMS made sense and contributed greatly to society. Nowadays - not so much.
It isn't worth it to restrict freedom of creator and force him to write open source software for minimal increase in the freedom of the users, when there is already an open source alternative for the given task.
The most-used operating system in the world has a Linux kernel. But, it might not be in front of you...except when you're checking email, waiting in line, playing Angry Birds, making a photograph, or checking up on Facebook.
I'm not a fatalist, I'm just pointing out a fact. FOSS is far from winning.
FOSS has barely "won" the lower levels of the stack and the highly technical niches. But the more you move towards user-facing applications, the more proprietary things become.
In a world, where almost all software was proprietary, and open source only made sense if you're living in towers of academia - RMS made sense and contributed greatly to society. Nowadays - not so much.
It isn't worth it to restrict freedom of creator and force him to write open source software for minimal increase in the freedom of the users, when there is already an open source alternative for the given task.