For a lot of us it feels like, if they knew the full story, they wouldn't be as harsh on it since a lot of the misconceptions come from Ufotable's decisions. So we try to fill in the blanks, but it's hard to replace what you actually see.
Like most people have a problem with Shirou because they try to relate to him and can't, so they're like "why is he doing that, what's he thinking?!" but the whole point of his character is that he's supposed to be someone nobody can relate to. It would be like trying to relate to Kotomine.
This is all spelled out a lot more when you have pages and pages and pages of text from his own point of view.
It's not the show itself that people are defending, since the show can have its own flaws as a portrayal. It's that these flaws are then assumed to be the fault of the source material.
Also a lot of the criticisms ignore any subtext and just act like if it's not spelled out via exposition that it doesn't exist. FSN Is a kind of show that likes to drop hints and let the audience figure it out for themselves. Personally, I enjoy that type of thing because it makes me focus on the show more (more replay value), and feel smart for connecting the dots. But you probably wouldn't like that if you want everything to be up front. I enjoy both types.
