the floors are sized for satrength and support of the rabbit's feet. They also are sized to exclude predators by default. That is why the same size is often added as baby saver wire. Poeple use ix2 wire to save money-- many rabbits cannot get through it once they are a few weeks old, it is less expensive, and still remains strong. the floor wire sizes--1/2 x1, is great for exclusing most predators--including rats weasels, and mink. So, unless the cage resident has a body part, like a toe, sticking through the wire, they are generally predator safe.
So-- larger hole, less expense. I have a 5 hole bank made of all 1/2 by 1 floor wire-- it IS quite sturdy, and have had no issue with predators-- but it was expensive to build-- that bank easily used a whopping 100 feet of wire-- it was made without my input!! Even the divider walls are 1/2 by 1-- It is YOUR decision how you want your cages to look, and what the wire sizing will be, both in gage and spacing.
In wildlife rehab centers-- the aviaries and other resident enclosure are often All 1/2 by 1 wire-- because the minks and weasels always find the ducklings, crippled up possums, etc....
