I know that the Multiplayer was incorporated into Reach to avoid splitting the player base, so this is just a thought.
What if they would heve allowed us to play Halo CE Multiplayer on disc, without matchmaking, just in a custom game setup. On old graphics even. Who else would have liked that?
Still wouldn’t be possible, Halo CE Multiplayer had no sort of network built into it to ever support such a thing, adding it would have changed the way the game played.
The problem isn’t making the game work in matchmaking, it’s making the game have online capabilities. Halo CE didn’t have anything built for online so they’d have to make it from scratch which could take them up to a year to make.