I'm fairly sure that open adoptions can have benefits for some of the children involved.
Regrettably, it reduces the pool of people who are interested in adopting.
I hadn't realized how very very negatively some people view open adoptions until a get-together with a friend, who was explaining why his sister was adopting from China for the second time. She was willing to expose her children to their culture of origin, but she was not interested at all in the possibility of any contact, EVER, with birth parents/families. She and her husband had been on the waiting list to adopt here for many years, were nearing the top - then discovered there really was no such thing as a completely closed adoption available. Ka-boom, off to China they go.
When I brought it up in conversations over the next couple of years, turned out it wasn't an unusual reaction to current adoption policies/politics. I was the only surprised person.