consistency isn't just for icing
What does icing have to do with creative design? Most of the time consistency is judged with the eyes, if it is runny or crumbly we typically form a negative opinion, it could taste right, but chances are we won't taste it if it looks bad.
Same rules apply when it comes to creative design, online and print materials have to be consistent. Your online and print materials become the first impression of your company. Everything that has your company's name on it HAS to look good and be consistent. If not you will lose potential customers.