I think that the summary hits the spot. These extensions would be a really good idea, but there are whole Suburbs that have no rail infrastructure at all! Implementing any Train and Trams in these suburbs would be a much better use of resources than providing inner-city yuppies with a way to save their boot leather.
Walking 10 km from Berwick or Cranbourne station to Clyde North is a much less pleasant journey than walking 1 km through Carnegie.