I ride my bikes hard which result in wheels that go out of true sometimes. If you’re miles from home, an out of true wheel can stop you cold in your tracks. If you have caliper brakes the wheel won’t be able to turn anymore against the brake pads. Having a spoke wrench on you at all times will allow you to bend the wheel back into true on the fly.
I have the Avenir wrenches that only work for one size of spoke each. I accidentally discovered that they dual function as a key ring for your house keys and bike lock keys! It also means you’re less likely to lose your spoke wrench, and more likely to have it on you when you actually need it!