Agree that it would be useful to us hosts and would be nice for Air B&B to come up with a solution.
HOWEVER - from a guest perspective, the Host Reviews are part of the selection process. Who wants to book based on an awesome Host with a reputation for bringing fresh baked muffins in the morning just to get swapped to a Property Management Co who uses "Dear Guest" templates and knows nothing about the house or community.
Sorry - I know this is a Non-Solution post, but I do think a little context/perspective helps guide us Hosts toward finding solutions.
When Air B&B couldn't help me switch a guest to another host (long story- my fault) I communicated directly to the guest and they seemed happy enough to re-book with the new host with a mia-culpa from me and a hefty discount.