Not sure if this has been suggested yet, I'm sure it has at some point.
I think it'd be kind of nice to loot people YOU killed (on the other team, team killing wouldn't count) to get more ammo.
I don't think taking all of the ammo or grenades is the best idea, maybe just a few bullets and a chance to get a grenade, if they had one.
The reason I'm suggesting this is because sometimes you run out of ammo entirely and it's either not possible or not easy to get back to the base alive. Of course it would be easy to just respawn but if you're in a good spot you don't want to leave, even for a little while, especially if it's really hard or not possible to get back there (like say you invaded the other base and found a good hiding spot or something).

Just my suggestion. Tell me what you think.

if they ever do implement this, you should have to walk on the dead body to get the ammo, or atleast get near them so it doesnt encourage camping.

I like it. ^

It would be cool if there was like a 25% chance you get a grenade if the person you kill hasn't used them or something like that.

yeah, good idea, I think it's been suggested before. I think that it could also drop the ammo and the gun separately, so you have to pick up both, maybe by clicking on them or something. it does this in red orchestra, and it's pretty cool, especially when you are picking up a sniper rifle or LMG, or an SMG, when you have the bolt action rifle

^I do and don't like that idea. Switching guns could be cool and annoying at the same time.

Picking up ammo would rock though! Maybe only the people you killed and 5 bullets/semi 10-15/smg 4/shotgun?

^That's a great idea. :D

Seems like this is being suggested a lot. I'd say it's likely it will appear in a future update, as it's a pretty good idea. Definitely something I'd like to see in the game.

^Ditto

i think it should be a full clip of whatever gun you have, a grenade and 15 health. You've got to remember that one of the most common sights are one man armies, or small collaborative squads. This means that if you're defending AGAINST these groups or individuals, you will be spraying a lot of ammunition before you kill someone. You will get shot at least once. These encounters happen typically in the middle of the map. It is likely that the rounds, grenades, health you lose will not be fully replaced by ypur dead enemy. On the flip side, campers will not want to leave their hiding spots for 5 rifle rounds and the CHANCE of a grenade. Their risk has to be worth it so they can continue their killstreaks.
Also, if there are large fire fights, more people around means you will be shooting more. More so than against campers or squads. Allowing the winning side of these skirmishes to means they can continue their push with out retreating for health/ammo and faster gameplay.
And in the long run, 8, 10, or even 30 rounds isnt a lot, and you can lose both of your original grenades from only two mouse clicks.
just something to consider.

I'd like to be able to pick up ammunition from kills. It'd definitely discourage camping.

I also think AnacondaML hit the nail on the head.

^^(Anaconda)
Summarized my opinion on the matter.