I'd say they should be changed if they have failed. However there are a number of reasons why the vehicle may have excessive vibration and it is necessary to consider and rule out other causes. Some basic troubleshooting is to try shifting to a lower gear, or neutral, while at a constant speed. If the vibration remains the same then it probably isn't motor mounts. Given vibration at highway speed (80 km is approx 50 mph) personally I would first look at tires (out of balance?) or wheels (bent?).
Patriots/Compasses are famous for failed motor mounts, creating vibration while stopped at red lights etc.
The mounts are a pretty simple item, and rebuilding them yourself can be an interesting little project.