It’s also arguable that converting St Kilda and Port Melbourne lines to LR provided a better service, hence the reason for congestion on the St Kilda LR. A victim of its own success, as it were.
Whilst the St Kilda train might have been quicker point to point, the LR (Route 96) offers a more convenient door to door service. At the St Kilda end, the train finished, obviously, at the station whereas Route 96 continues via Fitzroy Street round to the Acland Street shops and Luna Park.
Between St Kilda Station and Port Junction, there were 3 stations on the rail line. Route 96 has 6 stops. The train took 8 minutes, whereas Route 96 takes 10 minutes over the distance.
At the Flinders Street end, the St Kilda and Port Melbourne trains terminated at Platforms 10 & 11. At the time of conversion, the City Loop had only recently fully opened, a catalyst for development in the northern CBD, eg Melbourne Central and the Queen Victoria Hospital site. The only way to get to Parliament, Melbourne Central (Museum) or Flagstaff was via a City Circle from Platform 14 (formerly Platform 1 East), a four minute or so walk. (Sandringham passengers can interchange at Richmond.) Route 96 runs past Southern Cross (V/Line access) and the length of Bourke Street (apart from the Docklands bit) up into East Brunswick.
Port Melbourne seems to plod along just fine, with its 150-pass C-class. (Although through-routing to Box Hill appears to create some timetable adherence problems.)
As mentioned above, there have been significant cost savings over the last 30-plus years, for an outlay of less than $10 million (plus the cost of the B1 & B2-classes).
The demand on Route 96 might ease slightly with the opening of the Metro Tunnel. It’ll be quicker for some to catch a Route 16, or Route 3A on weekends, tram to or from Anzac, eg those to or from the Caulfield lines or some CBD destinations such as RMIT or Melbourne Uni. (Don’t mention the airport.)