I think this is a great idea, but in my experience there are surprisingly few such experts available. In practice, most statisticians not doing active methods research (I'm thinking of 'trial statisticians' mostly here, in CTU's) just cargo cult whatever procedures previous trials used. I guess they would pick up issues around sample size, but without also integrating that with some substantive knowledge about plausible effect sizes I'm not sure what value they would have.

Plus, it would reduce the number of publishable papers quite substantially including from high profile authors/groups, so I don't think they want the fight. We should also remember that most journal editors are also involved in publishing this research — they often have no real incentives to make things awkward.