I seem to recall my brother suggesting something like that to solve a number of the world's problems. If nothing else, he believed there would be full employment for many decades because of all of the work that would need to be done to tear down and recycle all of the empty buildings left behind.
Draconian? Yes. Practical or desired? No.
I recall a bstory written by Philip Jose Farmer called "Seventy Years of Decpop", where a scientist created a virus that left 95% of humanity sterile. He also created a test to determine who was still fertile and who was sterile. He released the virus when he realized that the world's population had reached a tipping point (9 billion or so). The story illustrated the social effects of forced decline in population.
At least this story didn't include a killing disease or a war to achieve those ends. Still, a chilling story.
I believe ABC has yet another doomsday made-for-TV movie about the Bird Flu coming out next month. From the trailers it looks like they're trying to portray Armageddon. Maybe that's what Dr. Pianka is hoping for.....