I think the government plays a huge role in setting the tone for the energy market.
The BCA has been asking for a policy for a decade. They still don't have one. While they weren't super enthusiastic about the NEG, they were happy to go with it as it could be tweaked as they went along. With a mechanism like the NEG or similar, then the government could largely get out of the way and let business get on with it.
Your energy reduction idea is good but of course it can only go so far. 20% per annum might be achievable for households for a couple of years but it's not going to cut it for business. A mechanism will encourage business to find ways to reduce energy use/emissions anyway. We still need to use large amounts of energy and that is only going to increase as global populations increase. So while planting trees, e.g. trillion trees program, is a great idea, it is only part of the solution.
Of course building renewables creates some emissions. But, what else are we to do ? Burning coal and planting trees won't get it done. Don't forget that in countries like Australia the power generation infrastructure is at end of life and needs to be replaced anyway. So, we have a choice. Do the same thing and keep increasing emissions or build low emission technology combined with things like carbon sequestration in soil and trees etc ? I think the choice is pretty obvious.
