The trouble is with the overcrowding logic is that more than likely without the occurance of WW2, most of us would not be here right now. We naturally assume that if there was no WW2 we'd be sharing the world with individuals who paid the ultimate price back then.
But without WW2, there would be no Baby Boomer Generation. There wouldn't have been any mad rush of soldiers coming back from the front, the air, or the sea. For example, my father would not have been born in May of 1946, after my grandfather got back from his submarine 9 months earlier. Life would have been normal with no WW2. Why have a kid then? Why have a kid at all?
Korea may not have occured due to the lack of WW2 and the Communist movement immediately following it. Jet technology wouldn't have advanced as quickly as it did without the German war machine. WW2 brought us many new technologies we take for granted now.
As unfortunate as it is, war does bring out new technology that will ultimately affect us in some capacity, for good or bad. Atomic warfare, jets, radar, sonar, ballistic rockets, etc.
It would be fun if there was a computer simulation program that had all world events catagorized and the impact on each other. If the user removes one event, what happens? Oh man, the hours you could spend making Alternate History happen on your computer screen.