Those planned sacrifices I definitely do not care for too much, especially when they prove to be more or less fruitless. The kind of sacrifice I'm talking about though is one of circumstance beyond the character's control, and with them reacting to the situation in accordance with their character. We've seen that three times now too, perhaps more, but only once did it lead to a character's demise. The damage done to the character is always quick. The specific events I refer to go with these quotes:
Oh, do not look at me so... A smile better suits a hero.
Ah, a magical barrier. Alas... It will not save you.
Noooooo! Don't you dare! We came together, and we're leaving together!
Even our ideal hero needs saving now and again, and they've actually been hammering on the point recently that the WoL can't save everyone. But, contrary to that, they seem reticent to actually let characters in the main cast really suffer the consequences of their own actions. If the WoL doesn't have the power to save them, then the scriptwriter does, and it's come to a point now where, we haven't had a major or minor death(or real, lasting consequence) in so long for the good guys that the world ending situation we're supposedly heading towards feels dangerous only in the most tenuous way.
As far as Zenos's intent goes... It doesn't really need to be personal from the outset or for him at all. I'm not saying that he needs to come out of his chair like, "Yeah, I need to fire my friend up by killing his lesser friends. The ones who use him." I'm more thinking that his and Fandaniel's plan still has steps that must be carried out. What happens if a few Scions get in the way where Zenos needs to be doing some killing and other such similar business? They'll clash. I would hope that the writers lack the temerity to have Y'shtola live through another subclavian artery wound (taking a wound there has the victim bleed out in 4.5 seconds). Or any other person he clashes with.
As far as who Zenos is most similar to from other Final Fantasies? Hmm. To me he is most similar to Exdeath from FFV. Was defeated once before. Had a walk about outside of his own body, possessing other bodies in order to get his body out of storage/back. Thirsting for more power despite already being powerful enough to wade through 99.9% of the populace as though they were ants. Completely roflstomps the heroes on their first few encounters. Power he's after has world building and world ending proportions.