Many of my animals are kept permanently, "clinically" in plastic boxes measuring 56 x 40 x 17 cms (22 x 16 x 6 inches). These boxes are easily ventilated, and can be stacked or put in a rack system. A non-bleached kitchen paper towel,which is dampened, is used as a substrate, with cork bark hides placed on top of one another, to create humidity gradients.
I don't include a water bowl, as I have seen fire salamanders drowned in even the most shallow of containers. They take all the moisture they require from the substrate. It is simple to monitor when livefood is not eaten, and when the substrate needs replacing.
A naturalistic vivarium is obviously far more attractive, but to whom? I doubt that the inhabitants are any "happier" in such an enclosure. I have had bacterial problems in the past with such setups, as it is more difficult to know when to replace/clean the various substrates.
My salamanders certainly breed repeatedly for me, and "survive" for many years in these simply maintained boxes.