Two things must be done to implement it on a broader scale (make it useful).
First: Grenades should explode upon impact after a certain distance, with a higher velocity to provide greater accuracy. Most of the time, the grenades will bounce out of the kill radius. A player's aim should have more to do with the kills than luck of the shot, otherwise there's really no point in aiming down the sights.
Second: it needs to not have a bright trail that says: "I came from here, shoot this guy!"
OR
The Alternative
Proximity airburst detonation.
OR
The alternate alternative
Remote Detionation as a secondary fire mode.
-Detonation would be done by pressing the fire button again, or right mouse.
Also: None of the non-bullet weapons award assists. That's right: not the K-Volt, X-43 Mike, JAW, Grenade Launcher, or L-TAG award assists. Ever.
Disclaimer: I have reached 100 kills with the L-TAG, I know how it behaves, don't tell me that it shouldn't be changed, because it's apparent that it's almost useless outside of crash site.