Goddamn, I never expected someone to basically rant about Fate/Zero here...
Well it's a good thing you did it here as I would have asked the mod to remove it from the Nasuverse Threads otherwise.
I won't disagree because I actually agree that Fate/Zero is a TERRIBLE introduction to Fate and hell, to Kinoku Nasu's world, in general(There's a reason why Nasu declared it to be "another timeline" as soon as the first volume was released and why he stated later on that the prequel to F/SN only has the barest of blueprints to Fate/Zero.
Saber's entire characterization in Fate/Zero is so absolutely out of character, Nasu has even stated you have to see this variant and the F/SN variant as "two different characters" despite the fact that's fundamentally impossible(So in the simple case, Nasu is saying that she's basically not even the same person). To put it in the most simple example possible:
Urobuchi never got Saber as a character until well after F/Z was completed. This is why she acts so chivalrous and "honor-bound" when that was not a major part of her character(She explicitly winced and didn't want to announce herself when Sasaki Kojirou introduced himself in UBW and when he told her he did it just out of his own reasons, she didn't do anything else). If anything, she's exactly someone Kiritsugu should like by how he's presented in the show: Someone who will do anything that it takes to win, even dirtying her hands and just ganking someone if she has to. She obviously won't go to the depths Kiritsugu would go but she absolutely would kill a Master if it's the way she has to win(Which makes sense as Garden of Avalon, which goes over how fucked her reign was in terms of everyone wanting to fuck her over, has stated... which came out before F/Z).
Hell, the entire point of Saber getting diminished as a person and as a king is meant to somehow get her to her F/SN characterization... when that makes no sense because in Saber's perspective, she's literally dreaming before she dies(Meaning the difference between F/Z and F/SN is literally NON-EXISTENT from her perspective) meaning she can literally just dismiss it as a dying nightmare and ignore all of it nor would change anything about herself in such a small difference of time.
Kiritsugu is even worse as the anime tries and desperately takes alot of the grime and ultimately how much of a child Kiritsugu is by trying to more or less portray him as a badass who just gets broken due to how fucked the world is(This is genuinely a huge part of the issues in the anime). The entire problem with Kiritsugu is that he's supposed to be a man who never grew out of the tragedy that happened out of his village and ended up adopting the worst aspects of what we see from EMIYA and Shirou's philosophy(Which came from him) and was so hollow, Saber explicitly stated the only thing he ever told her outright... was to destroy the Grail. The anime and LN, in trying to make Kiritsugu far more sympathetic than he is(F/SN has it to where it's heavily implied Kiritsugu truly did betray the Einzberns and Irisviel in a very cruel fashion vs. F/Z where it was just him using the Grail for his own wish behind Irisviel's back who most likely did know it already), completely misses the point of his character.
But it's actually Kotomine who gets it just as bad that most people ignore. The entire point of Heaven's Feel is that Kotomine knew virtually from the jump that he was born twisted and that he HATED the fact he was born twisted. Him going through everything he did was an attempt to try and go past his own nature but constantly failed to the point he just planned on killing himself and went to go see his wife one last time. She sees that he's broken as shit and basically kills herself(she was already ill) because she believed his grief in her death would show that he's a good man at heart... but his actual feelings(That he wanted to kill her himself) just completely broke him.
The key difference in alot of what we see of Kotomine in F/SN is a man who comes off like he enjoys being evil and revels in it... actually DESPISES IT AND HIMSELF and his entire point in wanting Angra Mainyu to be born is to ultimately get his question asked of "If someone is born evil, how would they react to it?". In F/Z, Kotomine is basically treated as if he never knew this fundamental part of his character, Gilgamesh has to basically force him to be evil, he enjoys being evil until suddenly he causes the Fire of Fuyuki where he suddenly just snaps into his F/SN side(or what Urobuchi believes it is) on a dime.
There is alot of things you can complain about with Fate/Zero because yeah, it's basically just missing the fundamental point of Kinoku Nasu's world just to be the "Bad Ending".