Dynamics AX is built on the Microsoft technology foundation provide but a number of platform software components. This gives you the ability to leverage that software to do more than you would if we have a propriety way to do something. Way back in the early days before the product was called Dynamics AX the report writer was unique to AX. While this provided simplicity it was lacking a lot of capabilities. SSRS reports were first introduced in AX4.0 and have been improved through AX2009 and AX2012. Because of this capabilities this then enables other capabilities.
In this example using a data feed from an SSRS report gives the users of Dynamics AX another way to access the data in the application.