As with most things, one size doesn't fit all! In my opinion (from a HR/Recruitment perspective) sometimes asking for Australian experience is justified and other times it is used as a reason to not select someone. It depends on the job, the applicant, the recruiter, the organisation, the skill set, the circumstances surrounding the role requirement etc etc.
My OH working in IT (and also being involved in recruiting staff in Adelaide) has found his skills have been in demand from week one and he didn't have any Australian experience when we arrived. He works within a diverse team with employees from England, New Zealand, Sri Lanka, India (gets interesting in their office when cricket is on!!), Ireland, Philippines and Malaysia.
There are also organisations in Adelaide which have a 'reputation' and locals steer clear of, (this can also be the case with 457 visas where they struggle to recruit to the position). The positive of this is that as a fresh off the boat migrant they will probably hire you straight away, so if you can stick with it for 6-12 months and gain local work experience, contacts, an Australian referee then move on to bigger and better things. You just need to understand how to handle the situation.
I think people need to ask themselves (and be honest) why are we emigrating, what are we looking for? If the top of your list is about your career and the money you will earn (and there is nothing wrong with that, if that is your motivator) then you need to make sure you carefully research if Adelaide can offer you that.