Apart from the fact that there was already a topic dedicated to multiplayer, I believe your conduct was proper
I understand your disappointment, and I expressed similar feelings in the other thread (I described the game as "cynical"). Personally I wasn't expecting so much out of this portion, so I am mostly satisfied with the honesty and fairly creative effort on display ; the game is forthright about the treachery of its reward system, and one truly gets a sense of the surrounding decay. It just stops there, like you said.
Thinking about how narrative could have been integrated better, one idea comes to mind. Perhaps they could have made access to new game modes a part of the levelling process, on top of the (expected) perks and (slightly less-expected) audio logs? Suggested social unrest through the implicit, shifting dynamics of the gameplay? (for example, matches with heavy emphasis on teamplay giving way to increasingly selfish odds) Surely this would have frustrated power players who don't have much care for such nonsense (and beginning players still unfamiliar with the rules of basic deathmatch)... but still, why not propose a more structured, non-mandatory "story mode" anyway? Waste of resources? Pointless complication of a simple foundation? Or just too idealistic? I'm just asking...
All of this just makes me wonder how MAG, without properly constructing a fiction, manages the internal structure of its crowded matches in a way that makes the slightest bit of sense (if it does), and avoids overwhelming the player with what is clearly beyond his immediate reach. There may be lessons to learn there.