Eh, it's current design makes the construction, the urban expansion (both of past, and of potential future, given how extended and incomplete the "stem" appears to be) and the change it was likely subjected to over the course of millenia more apparent, as it should be with a city older than the Covenant itself. A massive cruiser would just fail to have this effect, fail to convey that it is a city under constant change, and has been so for ages. I mean, cities expand spontaneously, and are never supposed to be static.
[Edited on 08.18.2011 5:32 PM PDT]