OK all, take a deep breath and think this through.
IT IS A REALLY STUPID IDEA!
On the one hand we rabbit on about the lack of experienced career pilots in GA - and then some bunny proposes something that undermines GA as a career even more.
A CPL is the basic entry level qualification to a professional career as a pilot.
If you want to enhance your basic flying skills and discipline - do a CPL! I don't care how experienced a PPL you are. Don't do it with some baby faced 250 hr Grade 3 - go seek out one of the multi-thousand hour Grade 1 Instructors that you might actually learn something from.
If you are a PPL and you want to instruct - do a CPL and an Instructors rating.
Lobbying to facilitate experienced CPLs gaining an Instructors Rating makes more sense to me than allowing PPLs to instruct.
I haven't looked at it for a few years, but you used to me able to do a C-Cat in NZ in about half the time required for a Grade 3 in Oz. Having flown in both countries, I haven't noticed any difference in flying standards.
If you want to be a PPL Instructor - go join RAA!
Dr 
PS: I was a 1000+ hr, aerobatic endorsed, PPL before I did my CPL and Intructors rating! I am a far better pilot for having undertaken CPL training!
PPS: I wonder how many CPLs think it is a good idea for PPLs to become instructors? Always seems to be the case that it is the people who dont hold the qualification who push to have the standards reduced!