The basic principle of growing the business is finding the best person to get the job done, with reasonable cost. That is why the payroll is outsourced to ADP; In-house Email Server replaced by Google Apps Premier; Business contacts are managed by Salesforce.com.
Your in-house data storage will grow as your business grow. Over time, it will become expensive. For example, it may take a couple of days to backup 50G data to a FTP server. It will take 200 days to do the same thing for 5 Terabytes of data. Your business premise usually is the slowest link to the Internet. It will not be a good idea to have local storage grow to a level that it is difficult to transfer to a different location over Internet.