I think it's a bit different for say shares? To be able to carry forward any losses from shares against tax from other income you need to be assessed as a share 'trader' as against a share 'investor'. The latter can claim the 50% capital gain concession but not tax loss against other income. I doubt most share investors would call it a hobby, not with real money on the line.
I agree though, it's a murky area that needs cleaning up.
How about $30,000 tax free and 30c in the dollar for the rest. 25c in the dollar for business tax? The ATO would cringe at the thought of 90% of them losing their jobs.
