Agreed. I'd definitely like to see this on the S ranks and I feel the A ranks could benefit from similar treatment.
People complain that the open world is dead, the Hunt is one reason to get out and explore it. In high level areas it's a fun and social experience, in ARR more of a gamble if you will arrive before the mob is dead. It's frustrating if you arrive late and often leads to arguments.
I'd like to see S ranks requiring a group no matter where they are.