Why so much concern about the population?

Why 343 concerns about the population and the game has been 5 months old. Why so much concerns about the population already? Well, 343 concerned the population from the launch and that provides 343 an excuse for having less playlists. Seriously, there should be an independent playlist for each Capture The Flag, Strongholds, and Assault right now. Even the population is low, Halo is 4v4 match game. I believe there is enough people to play Halo game. If population is low, try to bring back players with contents, not thinking how to make playlists less to keep current population. In addition this is my hope playlists for Arena after the last update.
-Team Arena (HCS playlist)
-Slayer
-Capture The Flag
-Strongholds
-Assault
-Odd Ball
-Infection
-SWAT
-Free-For-All
-Multi-Team
-Griff Ball
-Or 343’s new Arena game mode

If you use the search bar, you can find the population thread to discuss this in.