This feature is present in CC3, you can export FBX files containing only the motion, not the mesh. It is a very useful option, because it saves time and disk space.
However, if you collect / create several animations for a character and want to export these animation for use in UE4, it can be annoying to always having to open the character in CC3 and add the motion(s). It would be a huge time-saver if you could directly export the motions from iClone.
And in the case of props or rigs (e.g. a car), there is currently no way of doing this, because iClone doesn't have that option. So, please add that feature to the iClone FBX export function.