At this stage recruiting still seems to be MEL only so when they slow that down they might be looking elsewhere.
Also having bases in BNE and MEL means that there are plenty of staff only a short flight away from SYD if the need arises.
As for the rest of the country, they are allowed to use cross trained staff to do both ground crew and cc if the need arises so why have a permanent base when you can just use these multi skilled people.