We lack a lot of content in this halo I think that 343i should be open to putting custom maps into multiplayer.
We have had a very good share of memorable maps in halo 3 and halo reach that were built from forge, those maps were very balanced and symmetrical. MLG even used forge maps in halo 3 with no balancing issues.
They are already open to doing this but it takes time to test these maps and ensure they are non-exploitable in matchmaking.
They’ve actually already added a few community Breakout maps to the Breakout playlist and a community BTB playlist is coming in the future to test new maps before being implemented into the actual BTB playlist.