OpenGL is more for businesses, with CAD programs, and 3D modeling programs.
They use OpenGL because it's 'open' enough for any programmer to write a code that will show new things,which I think is not the case of Direct X / Direct 3D.
directX has preprogrammed stuff that game developers need to use. Lucky for game developers the functions and possibilities in DX10.x are so many that nearly all possible thought of effects and image generation that could be present in a game, is included.
Those newer versions of DX allow very realistic effects, like water, sunrays shining through objects, and reflections.