Since several days when searching a place you get only results with instant booking as results. This means all the hosts that don't use instant booking will get a lot less bookings. I totally understand that AirBnB wants to make it easy for guests to book a room, but not really nice for hosts that have good reasons to not use instant booking. It makes me think again that AirBnB pushes instant book even more.
I suggest to do it different. Not instant booking is relevant for the results of your search but the time a host takes to react. I will always react in less than one hour, so a guests nows almost immediately if I will accept his or her inquiry. Hosts that are not so fast are lower in the search results. That would be more nice for all the host that wants to know more about their potential guests.
And besides that AirBnB can give guests the option to book instant (but not make it default).