Quick note -- This only affects the host of the listen server. Clients that join will see the host and other clients properly interpolated. The host of the listen server will not see any interpolation on players whatsoever. If a client enters a vehicle, the vehicle's movement will be interpolated, but the player's animations still will not be.

The reason I'd like to see a feature like this is for situations where the base mission you're building off of may be broken in a way that requires editing or deleting original entities. In some cases, a broken mission could be fixed simply by deleting an entity, or editing the properties of an existing entity, like a waypoint, or an improperly configured player controller.

I experience this issue often. It's extremely frustrating and at times removes all sense of consistency from the game.