By a proper gradient I mean a linear white to black gradient. Surely this is just user error. There is no way this severe bug has gone unnoticed since 2.61.
On the left is a UV mapped image I generated with Photoshop. (Simple two color linear gradient.) On the right is a Blender blend texture. I tried all kinds of settings but none produced an identical gradient to the Photoshop one.
These are the settings I used. The gradient type is linear but the gradient produced is clearly not linear.