Great post, I think another thing that would really move the community foward to being more united in having fun togheter is the return of communication. I remember when I started to play online in Halo 2, in less then a week I knew most of the call-outs just from random people telling me. I was in no means a competitive player at the time, but achieving a win with communication and making friends along the way was the best experience I ever experienced on XBL.
When I look in my friends list, about 80% of them are from H2 (I dont even play with most of 'em anymore). With maybe 20% since H3 release. And back in H2, I had to clean my f/l every 2 weeks to make room for new friends. The only thing that changed this is the lack of players using mics online. We need to bring back the online community to the days that every lobby had 90% of users using there mics. We all get a mic with our xbox so there is no reason not to talk and have these "silent lobbies".
So I encourage all of us, if you don't already, plug in your mic and start talking to any players that have their mics, but with good sportsmanship. If you're the only mic user then just do call-outs like "I got a sword here for you", "sniper spawned", "1 shot on my X". Eventually players will mic up themselves to contribute and join in, the key here however is to be a good sport and encourage players to mic up. I believe if we really try, we could bring Halo back to its hayday of unity.