My take on "creating undead is evil" has always been that it's based on the logic that your standard undead is hard coded to kill everything it sees. While you can keep undead under control (particularly mindless undead), it's still putting everyone around you at risk; should you die or otherwise lose control of them, they WILL hurt innocent people if given the opportunity. The few undead that don't fit this clause are, at least going by Pathfinder logic (which I have played the most), not evil to create. JuJu zombies (which are intelligent and not inherently evil; they have no drive to hurt others that is granted by the template, though a JuJu zombie created from an evil person would be evil) are the prime example.

Going by the same logic, I'd say it is equally evil to keep some kind of other monstrous, cruel creature under control to sic on your enemies...which tracks with that typically being a villain trope.