The skeleton approach may work for some companies, but not for all.
For example, we do not directly insert skeleton files into our assemblies, we only include skeleton file parameters by linking through the parameter table. One reason for this is because we use a breakaway skeleton method in which the skeleton file is removed once the project is completed. This evolved from problems of skeleton files accidentally be changed and inadvertently updating other projects due to copy design issues from Vault. Linking the skeletons to many parts and assemblies via the parameter table allows the parameter name and dimension to remain intact and convert to manual entry parameters when the skeleton file is detached. When the skeleton files were included directly in the assembly and we removed the skeleton file from the project unresolved reference errors occurred on multitudes of assemblies within the project.
Bottom line is that a lot of people are asking about this and it would be nice to be able to extrude a surface in an assembly as a work feature. In a large company where we deal with thousands of parts efficiency is a huge issue. It's not very efficient to have to create an extra file for those who don't need to. It also leaves the door open for one more element to fail if that skeleton gets deleted or corrupt as opposed simply including the surface data in the assembly file with the other work features such as planes and axis.