All that's required for the MECIR is to sit and pass the IREX and do a flight test in a civil type you're rated on.
Of course there are good arguments as to why you shouldn't have to do either of those things to be given a MECIR on some civil type you're rated on, but it shouldn't necessarily be a blanket thing.
Take your knucks, for example - full marks to them, of course (personalities and watch-shooting bar activities notwithstanding), but there really is a learning curve to be negotiated before you'd want to have them leaving LSALT in their bug smasher on an engine-out approach OCTA.
Like you say, Shagpile, a comprehensive list of competencies for every conceivable thing you could get recognition for would be good.