DB - it's a dark and ****ty night, 200' cloudbase, strong winds, limited vis due to the heavy rain and there is a vessel aground on rocks (coastal location) with life seriously in danger and the conditions preclude lifeboat rescue.
It is an unfamiliar area and you are scrambled to the job - you have to get down from the cruise and get to the job - you are obviously relying heavily on the radar.
Not only do you have to let down to a safe area but then you need the radar to close to the coast until you get visual.
Would you rather have a well-trained radar operator whose ONLY job is to conduct that letdown safely, using all the skills and experience gained from training and being regularly examined in this discipline OR would you rather rely on the co-pilot who might have been up to speed when he did his type and role training but hasn't really got the best out of the radar and hasn't done a letdown in really poor weather for quite a while (for training or for real). Oh, and he is listening to 3 different radios, monitoring your flying and managing the FMS.
Tell me which one you think is safer and which you would prefer - I think my choice in the matter is self-evident.
ARAs are not SAR letdowns.