Those worried about 500FT vertical separation, have a look at ERSA for Sydney's chopper and Victor One VFR routes.
Been in for years.
In this instance if the STAR lined you up at 5.5 miles it would solve a few issues.
Essendon airspace and traffic as well as the height of the CBD buildings are limitations.
Also the noise associated with manoeuvring closer in over built up areas is a factor. These days any changes to and new SID/STAR procedures have to pass stringent environmental assessment.