Two adjustments to how fire teams work could be an improvement on the game, and lower the amount of unnecessary idling while using/snapping your messenger:
1. A "Request Invite to Fireteam" option. Good when you wish to join a friend's Crucible match (during the lobby could be a fair restriction), or even out while Patrolling; you could join a random's mission (a warning that your screen will be reloaded wouldn't hurt) and when the mission is complete, the option to return to Patrol directly or just back to Orbit could be very useful.
2. "Suggest Location" : While in Orbit in a Fireteam, a way to lower messaging (and mic use if that's your thing) would be the ability to choose the area you'd like to go to (of course, only available when you aren't the FT leader). Each non-leading-member's suggestion would be highlighted (or even sorted in its own area) on the leader's screen. This could also speed up communication when it comes to deciding to return to the Tower or continue your missions.
If there are any obvious flaws with my suggestions, please feel free to enlighten me. I've only recently began adding randoms to Fireteams and I feel some things should be communicable without a mic or having to idle.