Copying mix to cues sends does not work in a professional way and need improving.
When I want to copy the monitor mix to the Cue channels it is so frustrating having to select all the tracks first and if I am using group tracks the sound that is sent to the Cue channels isn’t the mix that is being heard in the monitor mix because of duplicated levels from the channels that are assigned to the group tracks. To fix the wrong Cue mix can be very time consuming if the project has a lot of channels and groups. It involves having to look at all the channels see if their outputs are being sent to any of the group tracks and if they are I then have to turn off their Cue sends. 
There should be a control or button that says Copy monitor mix to Cue sends using channel output routing assignment.
The user should be able to press a button in the control room mixer and a pop up box should open which will allow them to select the output that needs to be copied to the Cue mix. As Cubase already knows which channels are being routed to outputs it should be so easy to turn on the correct Cue sends and set the same levels and panning.
I am sure this is how most engineers would like to work, quick and easy and no messing around!