Gilroy’s not the studio, he’s an unrelated filmmaker that they brought in. If he says it was a mess, I don’t see any reason to doubt that.
And his whole point was that the first thing he knew the movie needed was an underlying theme, and sacrifice is what he came up with.
I can’t speak to Fan4stic, but from what I understand a lot of problems arose because the director was hostile or something.
Reshoots are 90% of the time a good thing and legitimately done to try make the movie better, though this is something the internet doesn’t seem to understand.
And I got your meaning, but like I said Gilroy’s right, if everyone dies in the end, the movie should be about sacrifice (in addition to those things you mentioned). I tend to think if they had more time they could’ve nailed it.