Creative Commons Share Alike licenses have many attributes in common with software licenses such as GFDL. Having some consistency between these things would make life easier for software creators looking to put a license on their work. It would be better if they did not have to choose between them.
No, the create commons attribution share alike licenses should not be made compatible with the GFDL, because each person who creates content should be able to pick exactly what kind of license they want to grant. Free licenses are not created equal, and both different types of licenses still serve their purpose in allowing creators to grand licenses as they see fit.