If it had genuine competition, I'd be happy to cut it much more slack on accountability, and wouldn't find its members-only approach or its confidentiality rules onerous. However, there is no real competition, and no clear path forward for such competition to emerge. Given that situation, I think it's worth considering that the W3C needs to be accountable to more than its membership. There was an interesting possibility for competition early on with the IETF, but the W3C and the IETF appear to have a non-aggression pact of sorts. Right now, that simple equation, which the W3C itself officially disowns, is definitely in operation.
Interoperability requires shared understandings.
Building shared understandings seems like a good thing to do. In some sense, it would be a step down from the W3C's current level of influence, but it would open a large set of new possibilities. Radical nonsense, I know. A Primer, 2nd Ed.