This idea has been permeating around since before Halo 3 was released, and I have supported it's implementation all the way, but the odds of it making it into H4 are minuscule at best despite 343i having ample time to include it. Main reason is probably the same as the reason Bungie gave as to why it was not included in Reach: "It would take too much time to create a whole new MM experience for custom games as there are too many variables to choose from the custom game settings, and we would like to spend that extra time making the Reach experience fully polished rather than 75% done with an extra search option tacked on".
Can't remember who said that but it was included in a weekly update back in the day I think.