The two pieces that really made it extremely useful for the game I'm working on was being able to 1) find/call methods from a script without knowing its name, and 2) find/ collect objects that don't have any similarities in properties/tags/layers/scripts other than inheriting from the interface.
It has freed me from making some arbitrary additional scripts linking these completely different object types and lists to handle and track interactions whiles also enabling each object type to react uniquely to a situation. For the longest time it just felt like interfaces were helpful in organizing and creating consistency, but now it's allowing for these cool chain reactions in my game that I didn't expect.
Not sure if that entirely makes sense with my lack of sleep!
Good luck!