Zenos should have stayed dead after his suicide in 4.0's ending. Since that scene he has done nothing to move the plot forward.
His character hasn't changed or developed either. Seriously, his big moment of significant change was the realization that the WOL won't fight him until this other threat has gone away. That's childish logic, not character development.
Post-Stormblood keep everything the same. Just delete scenes where Zenos is in another corpse.
Shadowbringers, Gaius should have killed Varis for knowningly courting Ascians. Estinien should have driven Elidibus from Zenos' corpse. The civil war still happens. Fandaniel takes Varis' body and the plot continues (remember they can make clones!).
Endwalker happens without Zenos entirely and we'd be none the wiser. Such an easy fix that you can't even love him into justification.
Not to mention all the lost plot threads, like the dreaming of Amaurot (So Ancient Zenos wasn't friends with Azem?), how does surviving death change you (because in this case it did nothing), and he just rolls with Fandaniel using him as a tool proving he has no self-worth (so why even fight the WOL at all if the Ascian is going to make you a puppet?)?
Zenos is a blemish on what was otherwise a well told story and expansion.