One of the main sticking points with the GFDL is the use of invariant sections, which may not be removed or altered (save for some very inconsequential exceptions.) One thing about the invariant sections is that the GFDL specifically states that they "contain nothing that could fall directly within the overall subject." They have thus typically been used to hold philosophical documents, licenses, etc.
I suggest that even if the GFDL did not allow modification of the invariant sections, if it at least allowed removal of them, we would be in much better shape. It would, for instance, allow people to better take the manual from program A and adapt it for program B, even if they disagreed with the GNU Manifesto or used a different license for program B. In the case of a manual that includes invariant sections, we could then throw just the invariant section into non-free, keeping the balance of the manual in main. (Or perhaps just delete the invariant sections entirely.) What do people here think about that, and is there any indication if the FSF would be amenable to this change? -- John