One thing that would limit feature creep would have the TLS WG maintain a POSIX reference library implementation, standard library compatibility interface (header file) and a comprehensive test suite. Because once the maintenance of that hits the people making suggestions and decisions, priorities will adjusted. (It still takes work to do the right thing regardless, but at least there would be a baseline, and behavior across implementations would be more comparable.)
Also, accelerate the sunset of older specs so that deployed code will have to stay more current to even function, rather than interop'ing with old code that will never be patched.