I freely admit that around 5.2/5.3 i was a bit nervous. ShB+ spoilers:
Emet was a terrific foil. He was mysterious. He was an active lore source, but from the angle of the unreliable/untrustworthy narrator. Most would agree that his actions were decidedly evil, and yet it was easy enough to understand where he was coming from. You could possibly see yourself in his shoes making similar choices(or at least struggling with them). For much of the playerbase beating him was a moment of confliction: you were happy to win, but a bit sad that it had to happen. Then we move from Emet(who we only met in 4.4 afterall) to Elidibus. Elidibus had been with us much longer(his first appearance was like 2.1?), but his character has been even more mysterious. At times he has seemed to be playing both sides of the ascian conflict. He didnt have a ton of characterization pre-5.0. But by the time we confront him in 5.3 we know a bunch more. And they present him in a unique way: the immortal who is forgetting himself but wont let go of his mission. We can feel for him too. But by 5.2/3 it is clear that Zenos and this new ascian will be center stage for the next expansion. Zenos is hit or miss, and by this point you have likely made up your mind on him long ago. The new ascian is an overly dramatic theater kid who took over the body of the worst(most hatable) character in the game.
So i was very nervous about how EW would go. The .4 and later patches dont change the characterization in any meaningful way, they just adjust around the margins. So starting EW from a position of not being sure about the villians is actually not at all uncommon. With that said, i ended up happy with where they took the story and the revelations we learned along the way. And about Zenos in particular. In addition to my playthrough, i have watched(in some cases helped) a couple dozen streamers in their playthroughs. Especially of the key ShB and EW scenes. And someone(i dont remember who i first heard say it) made a point about Zenos i hadnt thought of. The streamer was someone who has battled with depression for all their life, and they said that Zenos displayed a lot of the symptoms. Life is a never ending grey hallway. No one understands them, and theyve never felt accomplished. Then they had that one moment where the world came alive. They were content to let that be it, but for game reasons they were forced to continue on. So rather then slump back into that grey malaise, they did everything they could think of to re-create that moment. Also comparable to a long-time junkie chasing the feeling from their first high. Was any of this the intention? We can only guess, but i thought it was an interesting perspective.