The straights in Melbourne are not long enough, there are a lot of 90 degree corners and the track is flat and quite narrow in general, Turn 3 is the only decent place for overtaking, in my opinion. It might be easier in terms of overtaking than Barcelona, Singapore or Monaco, but it still much harder than many others. Meanwhile, Shanghai, Bahrain, COTA, Spa are wide tracks with a lot of runoff, long sweeping corners, heavy braking zones, wide apexes, medium-speed corners followed by straights, all of which allows diverse racing lines and provides opportunities for overtaking. As you said before, overtaking is very difficult in these F1 cars either way; mostly due to new regulations as the cars struggle to follow each other in dirty air and barely any overtakes happen if you don't count DRS, but a track layout still makes a difference nevertheless. Maybe it's more noticeable in other series than F1 though.
Personally, the only classic race I remember from Melbourne was when Ralf Schumacher flew over Barrichello, forcing at least a handful of other cars to retire as well I'm sure where were more, but that's honestly the only one I recall from otherwise "boring" track (in my personal opinion).