Reasoning:

1. Possible to replicate https://community.bistudio.com/wiki/addPublicVariableEventHandler this way, yet in a more generic way
2. Efficient event based coding possible this way
3. if its all your own code, you can execute code directly alongside ofc. however if the variable is 3rd party support (for mission makers/Zeus/mods) to toggle something on/off, this would simplify things a good deal
4. You can decouple state changes from the result code implications

Best case for all all the variable space - at least units and groups + namespace