The following is my personal opinion and experience on the importance of limiting data redundancies and increasing data integrity.
The reason why we want a very good database design is to minimize data redundancies and maximize data integrity. In general, data redundancies refer to whether the data in each record is unique. Integrity on the other hand makes sure that the data in the records is accurate and consistent. As mentioned above, normalization is enacted to ensure data integrity and reduce data redundancies. Thus, a poorly designed database can lead to many data integrity and redundancy problems that can negatively impact data sharing.
It is easy to imagine why data redundancies can be bad for an organization. For instance, from my experience working in the healthcare field, having multiple records for the same patient can be very problematic. First, upon querying the database, you may end up with the wrong record you are looking for, as it may not be the most up to date. This can be disastrous when trying to prescribe medicine. A doctor might see that the last visit on this specified record was 1 year ago, but in actuality, the last visit is one week ago and was specified by the other duplicate record. While this is a functional issue at work, it can also cause other operational problems. Duplicates will automatically make the database larger. Large databases can increase maintenance prices, decrease operation speed and increase complexity. Additionally, mistakes caused by redundancies can cause millions dollars worth of damage.
As well, you can imagine why data integrity is very important. Using the same clinical example above, data integrity ensures that doctors will be treating their patients based on their current situation and to the best of their ability. It will be very problematic if a doctor was treating a patient based on information that is not accurate. I had an experience like this when I went to the doctor for a broken right foot. On my record, it was listed as a broken left foot. Thankful, as a precaution, the nurse asked me to confirm if my left foot was the one broken. Precautions like this is what ensures data integrity. Data integrity can also have impacts on industries other than healthcare. In the business world too, I personally think owners and managers need accurate and truthful information to make decisions to improve their companies.