If the nose is set low then the main gear legs will be inclined backwards, causing the point of contact of the wheels with the ground to be further aft. The other point of view is that the CG will be further forward relative to the mainwheels, so the elevator will have to produce more force to rotate the nose upwards. Really overdoing it will stop the plane rotating at all whereas just a smidegeon will still produce an abrupt take-off.