Jijuboo41
The ZVV yearly NetworkPass, which is the equivalent of the Bonuspass, costs nearly 2300.-. My former employer asked roughly 800.- as personal contribution for the Bonuspass.
So if spending more than those approx. 800.- per year for commuting to work (or about 17.- per week in average), then that employer offer is a no-brainer.
As Roland already stated: The Bonuspass IS your ticket within the entire ZVV network, also for whatever leisure trips.
With a Bonuspass, your half-fare pass gets basically worthless within the ZVV, you’d still need it only for trips outside the ZVV. So if spending less than 170.- (half fare) per year on such “intercantonal” tickets, than you might consider cancelling it when getting the next renewal notification letter.