Battle For The Scarab ( Or Other Giant)

How com their has never been a sort of mode where two teams could battle for control of a Scarab. I remember a mission where in halo 3 with hornets and two scarabs. It was soooo much fun getting my cousin to fly me over the scarabs so i could jump on and take it out.

The object of control does not have to be a scarab, but some other weapon or vehicle that is on a large scale and can be piloted by one person. I know that we do not want it to be too big because of maps. However, with the new generation of consoles, sooooo much more is possible.

Any thoughts?