Exactly. While OpenGL is compatible with 99% of the PC gaming market, it is compatible with 0% of the console market. D3D is compatible with 99% of the PC gaming market, and 30% (very rough estimate) of the console market. Linux and Mac aren't even a blip on the gaming market radar, so why would anybody bother with OpenGL in a marketing sense?
The few that do bother to do it in OpenGL get burned when they want to port it to the console, because instead of a simple re-package job, they have to do 10 times as much work to move to a console. It may not be a massive amount of work, no, but it is more work than necessary. That cuts into your profits. Besides, there will always be less to screw up going D3D to D3D.