I would think that the reason some players do not see Zenos as a good villain is that they find absolutely no way to relate to him. He's not a tragic figure, he doesn't have a back-story of hardship and woe. He is not noble and true.

What is forgotten here? Zenos has a family with a peculiar background. The old emperor appears to have encouraged his upbringing (and don't tell me no one noticed as Zenos grew up). He appears to have some of the same characteristics as his grandfather, or else we would not have seen him past the 4.0 storyline.

Zenos is an enigma to the Warrior of Light. And that can be frustrating.