I live in a mixed SFH/midrise apartment neighborhood in Oakland, and our population density is 24,000 per square mile.
So putting 24k people in that part of Brisbane wouldn't even look particularly built up.
The Nob Hill, Russian Hill and Telegraph Hill areas (beautiful, treasured, highly desired places) in San Francisco all vary from 30k to 60k per square mile.
Putting 45k people on Brisbane baylands would be awesome.
What's really happening is that Brisbane loves the sweet tax revenues from all the businesses they host, but don't want the (expensive) responsibility to house all those people that work in town.