If you look at http://www.fsf.org/campaigns/, for pretty much every negative campaign, there's a positive one. The problem is that the positive campaigns don't really make the headlines. People want controversy, and the FOSS community communicates through echo chambers where people who yell louder win, so it's natural that the positive marketing sinks to the bottom.
The day before this article went up the FSF announced they were holding a planning meeting for a GNU social network. I only saw it thanks to http://reddit.com/r/gnu
Yes, more positive campaigning would be good. But I think it's unfair to blame the FSF when their positive campaigning falls on deaf ears. It's a property of the Internet and mass media more than a failing in the FSF. They have positive campaigns, we just don't see them as much.