Lets stick to the ordinary star destroyer at first. its like have a new ship that will not get the screen time it needs for serving that purpose.
We can achieve many things. First take the already established locations we saw in ANH and enlarge them to death.
Were it was a millenium falcon on a big hangar no we have a star destroyer in a bigger hangar.
Also showing how massive the second deathstar is and what capacity is capable to handle with no problem... even incomplete!
Finaly we can add Unicron eating the deathstar and have the space battle be over the cybertron ;)
-Angel
PS: that would be nice :P
Look how big the executor is :P(right click view image for full scale)
Maybe make that ship the villain instead of the ordinary death star ;)