Data has gravity
If you've wondered why many companies like Amazon armed with S3, Google with Drive even Apple iTune and Microsoft OneDrive are so eager to control data storage, the answer can be summed up in a simple term: Data Gravity.
Ultimately, where data is determines where the money is. All services and applications are nothing without it.
As data accumulates, there is a greater likelihood that additional services and applications will become attractive and appealing to this data they are cohering to.