Agree with your points regarding comments and multi-line strings; don't like optional commas, though.
With respect to your "lack is strength" argument, I can't help but find this unconvincing. We all know JSON is derived from JavaScript object/array literal syntax; your argument is akin to retro-fitting the requirements for service payload serialization to the suboptimal de-facto situation with JSON.
With respect to your "lack is strength" argument, I can't help but find this unconvincing. We all know JSON is derived from JavaScript object/array literal syntax; your argument is akin to retro-fitting the requirements for service payload serialization to the suboptimal de-facto situation with JSON.