Right now Bitcoin needs more standards not code before it can be integrated as a global standard.
A formal protocol standard is not always better than an implicit standard. Formal protocol standards are first and foremost an interoperability aid. The interoperability challenges of bitcoin are distinct from systems which are not blockchain systems, and it is not at all clear or given that a formal spec in the style of an IETF RFC would provide superior interoperability, without creating much more serious risks.
An RFC for the RPC interface would be sensible and has little potential to do harm. That would probably be a relatively non-controversial interoperability aid, and quite sufficient and appropriate to the w3c's interests.
Maybe you guys should start a thread in the "Development & Technical Discussion" section about this stuff, so that people actually doing the implementation may join in the discussion.