Never played it, but barrier ribbons were used to prevent guests from going to certain areas, and to control the flow of guests. They could also be sunk into the ground and still worked. It's a feature that would actually be extremely useful for Zoo.
Yes, I would also like to see this added in a future update. During a stream more than a year ago, Bo (former lead community manager for Planet Zoo), said she would talk to the devs about it but since then, we haven't heard anything.
It would be nice if a CM could tell us if the devs are working on it or not