I wonder if decades of fear mongering about birthrates might have something to do with it?
This is like saying "I still don't see why gravity is a problem when the overall height of the ball is still increasing."
The problem isn't today, it's tomorrow - after the large population starts dying off and the population starts shrinking. People don't live forever.
Let's do some math. Today, there are approximately 8.2 billion people living on the planet. The current rate of increase is that there will be ~2billion more in the next 60 years.
Even if the population starts declining for some reason, it would still take centuries even millenia before it becomes even remotely problematic.