As an example, we don't have a backup radar, and noone nearby have, so if it stops working, we work procedurally. Which we already do with traffic outside radar coverage.
Furthermore, our view from the tower is restricted to the north and south by mountains, which means tower separation is hard to achieve until aircraft are relatively close by.
So often asking if the pilot would like to request VMC climb after departure, saves us 5-10 minutes... otherwise we'll have to wait until we can see the traffic from the tower...
We're fortunate enough that 90 percent of the time, it's severe VMC... otherwise things take time..