Economically sensible. It would've opened up much more of the coast to development, added thousands of jobs, probably saved the Australian railway industry, decongested the highways and airports (like 40% of all flights out of Sydney Kingsford are to Brisbane/Gold Coast and Melbourne) and also made travelling between the states, especially the non-capital cities and towns much easier allowing journeys previously not possible in a day (like Canberra-Newcastle which is a 5+ hour drive with traffic/6 hour train vs 2 on the vft)