Being someone that didn't get a great ATAR back in high school, I think this is great. A university that is giving those who may not have done so well another chance to prove themselves. In a very competitive system such as the high school certificate, it is very easy to be consumed by the hype from rankings or the pressure of 'doing well' to get into x prestigious university (just a few examples).
In most cases, I do not believe ATAR is a good enough or justifiable measure for denying someone entry into university. This is why academic review processes are in place, to ensure that those who do not meet the requirements of university study either step up or step out.
When I completed Year 12 back in 2012, my ATAR wasn't great. This trend did not continue post-VCE, and my averages increased by a significant margin. Give a person the right tools and support to succeed at university, and they can turn their academic life around.
HOWEVER, in saying that, I can see the other side of the argument. In a profession such as teaching, accepting students with ATARs of 30 is ridiculous (in an undergraduate entry scenario, where they haven't had a chance to learn content in their areas). This is probably one of the only exceptions, as teachers basically engage in this ATAR/certificate based system and are expected to perform. I think all teachers should be required to complete a undergraduate degree first, then a postgraduate teaching degree to ensure they have the knowledge base to teach. I'm commenting on teaching as this is the process i'm going through at the moment.
I really like the idea of a second chance (someone has to offer it, right?) though.