I just stumbled upon this blog by Alex St. John, one of the creators of DirectX at Microsoft:
It gives a very interesting view on how OpenGL and Direct3D related to each other in the early days, within Microsoft.
Microsoft certainly was not anti-OpenGL. On the contrary, one could argue that Microsoft’s commitment to OpenGL is what made gaming a priority for OpenGL and the ARB, and made it a direct competitor to Direct3D. Be sure to also read the comments, as Alex St. John (TheSaint) posts some interesting background there.
It also shows that Direct3D managed to fulfill the goals it set out to achieve.
And although Direct3D did not quite evolve the way St. John had originally imagined, after he left, the chosen direction is not necessarily bad.
He also has a nice archive of old DirectX resources for you to download, including some very early SDKs and documentation: http://www.alexstjohn.com/WP/2013/02/08/direct-downloads/