As it stands, if you include work features in your iPart table, so you can use them within an assembly at a later date (for various reasons). Then they are forced on permanently. Since the members are read only you can't turn off the visibility of the workplanes/features which were included in the iPart table.
Please can you add the option to control the visibility of the work features in some way... or add support for view reps in the iPart Table.
Even if the visibility of the Work Features is turned off, you can still select them from the assembly browser for whatever you need them for.