It would be great to see allies being able to transport each other's troops. It would make for good friendships and improve the quality of alliances working together. Or if someone likes to build ships or aircraft even they get to focus on what they love most. Myself, I love the tanks... I want an army of them! Slow that they are, but my friend loves air craft and he's got his bombers and his transports to land me right into the action for a neat surprise attack. The enemy has a strong island to the west of us, my boat friend can send my tanks across and my air friend can come in right after I destroy those turrets! The boat friend is at the other side taking out the enemy's dock. All sorts of stuff can come about with being able to transport each others troops!