It seems that the strongest impediment to the Prince Street temporary housing is the addition of fill to the site, which will add to local flooding.
If the housing was built on concrete poles that put them above flood height and which could be later removed, it would probably be as cheap as, and less invasive than, the fill. After all, it is a temporary solution.
Houses would be designed to be easily removed to other sites. We are surrounded by low ridges. I assume the thinking behind this is that each house must have connections to sewerage and electricity. With compost toilets, stand-alone solar panels, and rain tanks, together with lighting efficiencies and the miniaturising of electrical products, it is now feasible.
Building on a floodplain has proven to be a bad idea.