It also increases performance by quite a lot. This increase in survivability allows the game to be more accessible to new players.
This makes it easier to survive the computer player's attacks because while the AI's growth is good, its tactics are average. A variety of units types and some tactics are required. A lower population limit makes it more difficult to defeat another player by using quantity of units alone.
I've been playing on both 200 and 150 pop recently.
