I think it's human nature, as often as I see it repeating throughout history (and not just in the tech industry). Just wait, there will be a new JSON just over the horizon which will close the circle and bring back a very simplistic serialization format with a minimal number of built-in structures.
Perhaps it would be better to create a C++ of serialization formats, all the features out of the gate, so you can pick and choose from the beginning. Again, I think human nature means we can't go back to XML (too much horror associated with SOAP and WSDL), or even continue with JSON (custom and subtly incompatible parsers being built around the core to handle missing features).