Marketing and mind share has long been the FSF's (and RMS') biggest problem. I'm quite sure that the term "Open Source" is used more often due to the absofreakinglutely idiotic decision to use the highly ambiguous and largely meaningless term "Free". When you have to footnote every conversion on the top to not only describe the term's meaning but also make sure the audience didn't assume you meant the more obvious definition, you have a very large self-inflicted problem.
Likewise, project names like GNU (or the "proper pronunciation of "GNOME") are just ugly and unattractive. Nobody likes guttural sounding words, at least not in English-speaking cultures.
The desire to force people to prefix that guttural name before the rolls-off-the-tongue "Linux" moniker is just worse. Not only do you make the name uglier, you make it longer! People use names like "Vista" not "Microsoft Windows Vista". People at lazy typists and speakers (again, especially in English cultures). If GNU had a less hideous name, RMS might even have managed to get people to that instead of Linux. There's just no chance in hell of getting people to say "GNU/Linux" in common usage,