I would agree with your interpretation. That would be a concern. We were tasked with recommending an electoral system that met certain principles, but we felt very strongly in our commission work that we had to spell out what that system would be and all the details; that we were charged with figuring it out; that the details did matter; and that the potential for unintended consequences for the various actors in the system, all of whom were legitimate, needed to be thought through as best we could. We had to come up with recommendations. Where we could, we came up with precise legal text as a way to encourage both the government and the opposition to actually move it along. We didn't want to leave very much to chance that things would get muddled at the other end.
So yes, to use your example, Mr. Reid, if you proposed MMP and had some rationale for it and gave no detail, I think you would be leaving yourself open to perhaps a different kind of system in important respects from what you had contemplated or desired.
If you're going to do your work, do your work. Do the detailed heavy lifting in order to help move the process along.