I'm personally against the concept, it's completely backwards. Those who can efficiently kill others and need no help...why do they get handed tools to kill MORE effectively and give their enemies even less of a chance (often zero chance)? When someone is that good, the last thing they need to be given several extra easy/free no-skill kills as a "reward". It makes no sense whatsoever and is impossible to justify.
Crysis 2 had moderately powerful killstreaks (still unnecessary for my tastes), but Crysis 3 went completely full-retard with killstreaks to the point of them becoming a core method of farming kills.
Just an example pulled from Crysis3S, you will find several leaderboard-toppers (not gonna name names) with Swarmer as their 2nd or 3rd best "weapon". Yes, a killstreak is their 2nd most effective weapon.
I guarantee they would have had untold thousands of kills with Orbital Strike, Ceph Gunship and while under the effects of Maximum Nanosuit. Maximum Radar is also a big help, it has a fairly high uptime due to someone in the team keeping it active.
Call Of Duty has been the main inspiration for killstreaks, so a lot of games parrot what it does in an attempt to cash-in to it's success. Either that, or the developers feel it's a genuinely good addition.
I personally feel it's something that needs to go once and for all. It doesn't help the game grow when newbies get obliterated over and over by more experienced players abusing killstreaks to slaughter them. Actually forget newbies, it doesn't help when respectable veterans (coming over from other games) just want to have a decent match without someone repeatedly insta-killing them with killstreak bonuses. They feel conflicted about stooping down to using bonuses themselves because the opponent isn't even given a chance to react/survive, the kill feels utterly meaningless.
If there was a future multiplayer Crysis title, and if you considered buying it, would you support the return of killstreak bonuses?