The host should be aware when accepting a reservation if the guest is likely to give a low rating.
The average rating given by a guest should be available for hosts to see so that they can avoid hosting those guests that are impossible to please.
This way guests would feel more responsible for their ratings and would help transparency, honesty and reduce nasty, illogical low ratings, that sometimes are given in a lighthearted way.
Also, when asking guest for ratings, associating 5 stars to the word "fantastic" might feel appropriate for holiday homes in beautiful locations (that are priced accordingly), but for the average, cheap-ish room in a shared flat in a city, even if everything goes well and nicely, asking the guests to say it was "fantastic" is a bit of a stretch.
I would remove the adjectives from the star ratings, it is misleading and pushes people to give 4 stars over 5, mainly for low budget rooms.