Why has the population control concept been discarded in favor of individual environmental impact reduction?

Question

It is common knowledge that there is a maximum sustainable population for this planet. It has been common knowledge since the 70's that environmental impact is a function of population, affluence and technology (I=PAT), with population being the biggest contributor, since everyone eats and drinks, defecates and urinates, requires resources and shelter. The logical way to reduce environmental impact is to reduce population (P) to sustainable levels. This method keeps individual quality of life (A and T) high, but somewhere in the 1980's this was abandoned in favor of reducing individual impact (reducing A and T from the formula), thus lowering individual quality of life. Why is ever expanding population and lower quality of life now considered acceptable by both liberals and conservatives? When environment first became an major issue in the sixties, it was the left that was concerned about unchecked population expansion and lower quality of life. What happened? Thoughts?

Answer 1

I think population reduction is really the best way to create a nice sustainable life on earth for the future.
Unfortunately control of reproduction will remain taboo until we are in a total crisis I think. As it is considered a very private issue and there would be a great debate about the rules of who can reproduce and who cannot. Making this more difficult is the fact it needs to be a global reduction of population.