Streaks should be limited in number. I suggest 5 tiers with two Streaks to choose from in each tier; One offensive, one defensive. Your first Streak should not be given to you after minimal work. You have to earn each Streak you get. They need to be spaced out more so that one good run doesn't net your first Streak which earns you the rest.
In Black Ops II you could get a Lodestar and with that alone it got you your Dogs and SWARM and most likely a good way into your next cycle and you still had two more high powered Streaks to call in. That needs to be fixed.
I'm glad to see the community wanting gun on gun action more with this title. It makes all my preaching worth while
Rather than get into specifics about a mechanic that I am sure is pretty baked...
... I'll proffer my POV about the the philosophy I hope Ghosts will use.
* Streaks should not be over-emphasized.
* Streaks should not recycle over a single life.
* Streaks should carry over between rounds (but keep what you've earned).
* Streaks should not chain.
* Streaks should stack.
I'm less concerned about the specifcs, TBH.
To the OP ...
You don't need 5 kills to get a UAV in Core TDM. If you are absolutely certain that it is necessary, then send me a private message via Activision and I'll hook up with you on XBL to show you how you can actually get a UAV in TDM with no kills at all. Certainly you can get a UAV with 2 or 3 kills.
Anyway, making it easier to get rewards will not reduce the emphasis upon rewards. Lowering the highest reward level will not help matters, either. I can explain using COD4 as the best example. Once you got your chopper, you would suicide before calling it in. Once you respawned you called it in and let the kills from it count toward the new set of rewards. Net result is that you would only have to get 2 or 3 kills to get another chopper. That's how better players spammed kill streak rewards in COD4. It is also the reason IW increased the number of rewards available to choose from and made their reward level go up to 25 (the nuke).