Right now you are effectively penalized for doing too well in an on foot conflict zone. The majority of the reward for one comes from the kills you get and if you do well, the zone is over faster and you actually get a smaller (significantly) reward than if you do poorly and thus have more time to get more kills.
By adding a tiered system for the rewards based on how many points you have left at the end of the zone, this disadvantage could be offset and a better reward could be given for particularly clean conflict zones. This might be useful in space based CZs as well, but I think those matter a bit less as they are more quickly reset, where as it is far slower to reset the ground based conflict zones, either running out to your ship and leaving and returning or taking a full taxi ride round trip.
By adding a tiered system for the rewards based on how many points you have left at the end of the zone, this disadvantage could be offset and a better reward could be given for particularly clean conflict zones. This might be useful in space based CZs as well, but I think those matter a bit less as they are more quickly reset, where as it is far slower to reset the ground based conflict zones, either running out to your ship and leaving and returning or taking a full taxi ride round trip.