I can tell you from my own experience why Allegiance loses players. There are other games out there. I spend my time playing Battlefield Bad Company 2 and Sins Of A Solar Empire. Then mix in some tv series and that's about the time I can spend on media.
Allegiance is small, the community is small. When I stopped playing the game, I was able to predict the outcome of a game quite easily by looking at the players on the teams. In other games this is impossible, because the player base is huge. Yes, I often stacked, because being whored on is not much fun. The times I antistacked, yes, some games were fun, if you were able to win despite your team. Anyway, even stacking becomes boring after a while and then I simply stopped playing. The long breaks in the lobby were also a major reason to quit. If I have 45 minutes to play a game, before I have to go to bed, I don't want to spend 20-30 minutes discussing the next commander. So I don't even launch the game and play something else instead or watch an episode.