Why Would I want Private Name Servers?
When you have your own private name servers it looks like you are running the hosting company. Instead of people seeing your web hosting companies name servers they see your private name servers. If you sell hosting and you do not want your customers to know who your web host provider is you would want your own private name servers. Another reason for having private name servers is that if you host multiple domain names, then you can update the I.P. address for the private name servers once instead of having to update the name servers for multiple web sites.