I was recently involved in an ACS "Re-accreditation" review for my University which I graduated from in 2011. It was clear from the outset that the whole thing was a farce - to be re-accredited required the ACS to ask past students generic questions (such as "How important is ethics to an IT Professional") and for us to give canned answers. While the university didn't explicitly tell us to give the 'expected' answers to ACS questions, it was strongly implied that we were expected to represent the virtues that the ACS "teaches".
It is in the universities interests to advertise that their IT degrees include ACS accreditation (despite no Australian IT employers I know of giving a damn about it) and it is in the interest of ACS for the university to keep paying the exorbitant fees. If anything, I feel that ACS accrediation is detrimental to the students as it requires the university to include such useful courses as "Ethics for the IT Professional" in their degrees. While being ethical is obviously important to any professional, this is time that could be spent learning real skills instead.
I did one of these a few years ago and it seemed like quite a formality, they asked vague questions about topics related to professionalism rather than any technical skill.
While I can understand that a professional body would want to ensure that people acted ethically and in good faith, I would think that it would be wiser to ensure that people graduating from technical, engineering related, and detail oriented degrees were just that. That way having an ACS seal of approval on a degree would carry some sort of weight towards the technical quality of the person, and hence would actually mean something.
Maybe it's the spaces and people I work with, but no one that I have worked with is actually a member of the ACS, despite being in industry for almost a decade.
As far as software is concerned, until we have proper liability for defective software, ala Civil/Mechanical Engineering (where one signs their name to the design to certify safety and fit-for-purpose), we have little right to call ourselves (Software) Engineers, and hence no real reason for a professional accreditation/certification body.
I also just looked at the website, and all of the membership levels look like rankings in a guild system to me. Spend your time, pay more money, rise in ranks. Protectionism at its finest, and even though I'm heavily a software developer, I'm still against this burden.
Liability doesn't make sense for a lot of software. It's not like electricity where it's always potentially dangerous, civil where mistakes can cause death and dismemberment en masse and so on.
Basically software liability is just rolled up into the relevant market. Writing facebook games? It doesn't really matter to society if you get it a bit wrong. Writing pacemaker software? Then you're governed by medical device regulations.
Software's application to problems are so varied, so wide, that it's insensible to apply a single liability scheme to it.
Those courses are mandatory because the Australian government now correlates generic graduate attributes with funding allocation. This means that all Unis have to show that a percentage of their graduates are competent in, and all graduates have access to courses in ethics, sensitivity, knowledge application, problem solving, and communication. Uni administration forces lecturers to integrate these into their courses, and they then deliver a half arsed rendition to the students.