Currently, if you copy/mirror/pattern a set of components, you have to remake all of the joints that constrain the copied components. It'd be great if there was a checkbox within these tools that said "Copy with Original Joints", so that the mates will be auto-generated within the components selected and copied along.
As a further development, integrate a joint copying tool so that you could select external joint origins that you want copied parts to fix to - say I have a bolt, a standoff, two washers, and nut as a set of components I'd like to copy, and I have a clock-cage gearbox made up of two plates and four of these standoff constructions. I could copy the components that make up the standoff assembly (bolt, standoff, nut, washers) with all of the mates they have with each other, and additionally select the joint origin that affixes those parts to the clock cage plates. I could then select the three other joint origins where I'd like to put the remaining three standoff assemblies, and Fusion 360 would automatically copy the selected components and mate them to the plates in the selected area.