To some degree, this is a good thing as it allows more of the tire tread to stay in contact with the ground during hard cornering. But if you have too much negative camber, which degrades cornering performance as well as hinders grip during hard acceleration.
The camber kit can straighten the wheels by dialing out the negative camber, something you can't do with the stock camber rod. They are also great for race days where changing from street tires to drag or race tires where the camber need to be adjusted on the spot. You can manual dial the wheel in by adjusting the rod in or out.