Have you ever just looked at forged maps in Reach and just hated how everything is so... Grey? I personally dislike the grey. It looks cool, but it's just an overwhelming amount of grey sometimes. If we're going to have just a single, super huge Forge map again, I think it would be awesome to have swap-able pallets or themes. As in, during forging in-game, or from the Forge lobby, you choose whether you want to use Sanbox Theme, Foundry theme, Forgeworld Theme, Space theme, Arctic theme, etc.
As long as we're not stuck with bland Grey/Blue schemes or other bland schemes, I'll welcome any change.