Why? They've come out of the closet. Not that Oracle's R support has been hidden on purpose, near as I can tell. But this is the first explicit discussion I've seen. Of course, you have to buy up the fancy version of Oracle to get R. Kinda ironic, what?
Oracle recognized the need to support data analysts, statisticians, and data scientists with a widely used and rapidly growing statistical programming language. Oracle chose R - recognizing it as the new de facto standard for computational statistics and advanced analytics.
C'mon MicroSoft and IBM, it ain't all that difficult.