I do think the streak system needs an overhaul. To be quite honest, I like how Ghosts has done it. The streaks aren't overpowering (though some seem to be, such as the Dogs) and don't dictate the game play like they have in previous games.
I personally like the Assault, Support, and Specialist streaks, as long as the Support streaks are truly support and the Assault streaks are truly Assault. People can complain all they want to about Support building even with deaths, but true support players are not always able to string together long streaks, so they SHOULD be rewarded for their efforts, as long as the rewards help the team and aren't high kill rewards like the Stealth Bomber, etc.
I love the idea of the Field Orders, however they again are leading to selfish, silly play. What if the idea of the Field Order was taken to the next level? Rather than Individual tasks, they call for the team to accomplish something? Instead of it going away when one player dies, perhaps put a time limit on it? Once completed provide an award for the whole team... such as ammo, Ballistic Vests... something of that nature.