Looking at that list, I'd be tempted to say that supporting OpenGL is a waste of time.
Support of OpenGL by hardware vendors is definitely not a waste of time.
OpenGL is the ubiquitous presentation back end for nearly all high end graphics applications. All professional 3D modeling and layouts programs use OpenGL extensively. Maya, Modo, Lightwave, Blender, XSI, Cinema 4D ect.
OpenGL is also the foundation of cross platform hardware acceleration for many graphics packages. Adobe, for example, takes advantage of OpenGL shader programs when available with most of their their products like Photoshop and After Effects, It will soon
be leveraged in Flash 10 where everything can be in 3D and users can write their own shader programs.
"OpenGL high-fidelity support in After Effects CS3 Professional includes support for blending modes, adjustment layers, track mattes, accelerated effects, anti-aliasing, 2D motion blur, lights, and shadows."
OpenGL is also the backend for all composting on those "other OSes" ... Linux and OSX.