As a molecular modeller using OpenGL to visualise molecules, I find the lack of true sphere support very limiting.
A typical protein molecule has about 3000 atoms to draw as spheres. These need at least 20 slices/stacks to draw: not exactly real-time to display.
Way back, I used an old SGI IRIS4D machine with the original GL code - which supported the sphere primitive. Why has OpenGL *still* not got this?