> our drivers don't utilize [Terascale] gpus significantly differently than the R200s

At least for now there's still a significant difference: one is 3D-supported, the other isn't :-)

> If the OS doesn't support [OpenGL 3.3] functionality, does it matter?

At least porting more recent games (OpenGL 3.3 is from 2010) may require newer OpenGL than MorphOS currently provides.