Something needs to be done to limit server size to the number of players for which NS is meant to be balanced.
In normal NS, large teams lead to terrible balance. Aliens have huge disadvantages in large games, and by large, I mean anything larger then 8v8 (and that's the largest I believe any NS game should be). Because marine upgrades are universal, and because aliens don't share resources, it take a huge skill difference or a lucky rush for aliens to win in large games.
NS:C maps are made for small numbers of players. When the numbers of players increases, the maps become clogged messes. Players are constantly blocked by other players. There is no "less used" route in larger games. 40 minute games are common and usually end when the aliens get sufficient onos to respawn faster then they can be killed.
Large games are not as fun (in the overall game, not individual battles) and lead to all kinds of balance problems (and complaints).