Use case: two User Groups: Internal & Client
In project Acme, both user groups have access. However, there are some Cases in the project that are for internal use only.
New feature would allow us to set it up so that only users in the Client User Group would only be able to view cases if they created the cases or if they are assigned the case (or have been assigned the case in the past). Not Read-Only (because we want to restrict what they can see and give them edit access to some cases). Maybe call it "Restricted" access.
Yes, we could create two parallel projects, with parallel areas, one accessible to Client users, and one not, and if the Client users need to see a case, then switch projects. But with over 100+ projects, this becomes a big administrative headache.
I realize that your policy has been: "Once you're inside the walls, we allow you to be segmented in to certain parts of the install, but when you can change something, you can change all of it. When you can see something, you can see all of it". Even so, I am posting this anyway, since I can see value and clear use cases for wanting to be able to restrict what users can see within one project.