I want to preface this with that i respect everyone's right to an opinion. But i do feel strongly about this, very strongly. This may seem rambling, but it's effectively a mixture of different messages i've typed elsewhere about Zenos as a character, just collated together to make some manner of sense.

I think Zenos is a good character and villain in the contexts he is presented in SB and EW. I also believe the fanbase has taken him purely at face value, when he is much deeper than any of the villains that came before him on a personal level. And also much more entertaining to watch and listen to.

The character has simple motivations, but that doesn't lessen what he is or what he represents. Zenos at a core is clearly suffering from some sort of severe melancholy/depression. He had/has nothing to live for, he was raised to be a monster, to fight and kill, and only ever found joy in battle. By the time we meet him he's almost drained because it's no longer fun to him, he kills and kills and nothing ever satisfies him. So he meets us. Someone who can match him in battle, he's able to actually feel something again. In feeling that, feeling actual joy for what is probably the first time in years for him, he just kills himself. Because he thinks he will never be able to feel it again, he's so overcome with joy and then probably sadness that he has felt something he never can again.

And when the dude comes back he wants to relive that feeling, literally an addict chasing a high. He's a shattered reflection of not only the player someone who just fights bigger and badder things for the fun of it until there is nothing left, but he also can be used as a mirror to characters like Hauchefaunt. Like Hauchefaunt he's utterly devoted to the WoL, almost obsessed. And both charaters are willing to die for them. Hauchefaunt willing to take a killing blow for us, and Zenos wanting us to effectively kill him.

In EW, more than once, he speaks about his perspective on life. How it was a suffocating muck, how he didn't understand the things others pursued, or found happiness in. That only one thing gave him that same spark, made him feel.

His motivations are just: Fight WoL, obviously. But it's his characterisation that is important to him, it's how he expresses that motivation, and how we drive him. I very much think that they are going to point out that our character would have wound up exactly like Zenos if it wasn't for the people around us. Someone who was just pointed at Primals and told to kill, fighting over and over again until there was nothing, not even satisfaction.