There are three general cases in which you might want to add your own data to the system.
You may want to add your own white or black list for integration in a feedset with other sources. Perhaps you're having some false positive problems that you could resolve by putting a white list in front of all other sources. Perhaps you've always wanted to run your own DNSBL or DNSWL? And if your data is useful to you or a group of others, maybe it would be useful to many others too. So why not share it and enable others to benefit from it too?