I agree with this idea completely and have felt like this should be an option for a while now. It would be very helpful. It's the default method for copying any component in Grasshopper3D and it's proven to be very helpful there.
I looked at the XML files for FF filters a while back to see about using Knime to generate upgraded versions of filters as a means to auto-upgrade my filter library to the latest nodes. Based on what I saw I do think this copy/paste option is something that could be done.
I would say though, as handy as this would be it would be nice to have both the current method and this new alternative as options. I haven't yet figured out how to copy/paste things in Grasshopper without the existing connections and it does tend to get in the way at times and slow things down when the nodes in question have a lot to process and I didn't care for the connections to begin with.
More options are always nice. Losing existing options in favor of new ones isn't.
So, let us have both