As a default it's fine, but they were opposed to even providing deserialization to Integer/Long as an alternative mode. I guess it's a question of whether and to what extent JSON serialization should be considered as limited to the type system characteristics of JS itself, when the notation is flexible enough to express non-JS concepts like the difference between ints & floating point. JS may only have a double but KotlinJS does have `Int`/`Long` 🙂