Fun fact about Chris Terrio AKA "the BvS writer guy," when he was announced as working on BvS people were excited because "Ben's bringing in his awesome writer friend from Argo to fix up Snyder's crap."
And honestly I don't blame him for BvS and JL, most of the blame lays at Snyder's feet. Writers can admittedly have much more of a pockmarked reputation, with past failures and triumphs not correlating as strongly for future work as compared to directors.
Chris Terrio and Zack Snyder were in complete agreement on BvS and JL and what would be then JL2 as an arc coming out of
Man of Steel. Terrio is the one who wrote the original
Justice League script that Warners deemed unfilmable which would take place after the release of the Anti-Life Equation and Superman under Darkseid's control. The arc would end in Superman's display of being the ultimate hero by ultimately resisting Darkseid and saving the day that the rest of the Justice League could not do incomplete.
They were ordered to rewrite completely and bring back Superman early. Then when Snyder finished his work cut, Warners deemed it unreleasable and hired Joss Whedon to rewrite it. Joss was given so much power (which he resisted having been put in that position himself) that when Snyder's daughter died Snyder told Joss he'd bail out and he should just direct the expected massive reshoots.
If you remember, the original tagline for
Justice League was #UniteTheSeven. There's only six Justice Leaguers in the film even after Supes is brought back to life. The plot makes no sense because it's two separate films mashed together, that's also why half the movie is the Justice League standing around talking because of the reshoot costs and the other half is some random Russian family doing close up reaction shots to things never shown on screen, they could only just edit the already done action scenes Snyder directed. Which is super obvious from looking at the trailers versus how the same exact scenes appear in the movie.
I don't think you can blame Terrio, Snyder OR Whedon. Warners execs wanted the film out to get their bonuses from it being released by a certain date. So none of the three got to completely script, shoot and finish a film. And Warners didn't think to impose any demands as to what the film
had to contain until Whedon was made director (officially only for reshoots but potentially for an entirely new film) and they already knew what they
didn't want from having seen Snyder's rough cut but were never going to give Whedon the time or budget to shoot it.
The infamous CGI'd off mustache was entirely unnecessary, Tom Cruise injured himself and they shut down shooting Mission Impossible, Henry Cavill could totally have regrown his mustache by the time shooting on it started again, but Warners didn't want to pay the couple million insurance agreement on it because they were pinching every penny possible having done nothing to stop the film's total budget from hitting $500 million before realizing they hated it and wanted it out asap. They didn't even use the same effects company but found the cheapest contractors available to do the hundreds of effects needed in the reshoots and edits alone.
This is why Warners completely turned around and confirmed the DCEU after cancelling it and all the related films not already in production, they assumed it was nothing they had done to
Justice League, it was the brand being bad and Marvel just being lucky. Then
Suicide Squad and
Wonder Woman both did near a billion despite being "dark", and then against literally all expectations
Aquaman made a legit billion despite James Wan getting to do it however he wanted because it was the least attractive character, and now the DCEU is totally alive with sequels boarded into 2022 and even Ben Affleck back in good graces with the studio and both him and Gadot now permanently owning producer credits. (Except Green Lantern, The Seventh Member, which they're still afraid of because of 2011's film and only was boarded in the first place because of Geoff Johns.)
Disney is making the same exact panic decisions Warners did, they're looking at
Solo's disaster (from the corporate POV of what was happening on set) and TLJ's heavy drop-offs and their own panic fussing over
Rise, ignoring that
Rogue One nearly did a billion despite the studio fussing endlessly over it, and even knowing that
Rise of the Skywalker will do two billion basically no matter what and this being a proven 40 year old brand. As much is made of the proliferation of film franchises it's hilarious that two of the largest entertainment corporations are being so conservative and paranoid about two of their biggest brands possible. They actually weren't/aren't throwing shit out as fast as they can to make bucks from China, they're treating the brands almost as if they'll become worthless overnight if they aren't handheld from top to bottom even though the MCU has proven all of this wrong about everything from the IPs themselves (
Guardians being the easiest example, but
Iron Man actually being the original and best) to the directors and writers involved to the studio oversight to fretting over the associated brands even though everyone is showing their ability to be totally capable of NOT BEING CONFUSED by multiple Spider-Man films happening plus all other Spider-Man media out there.
It all makes now the ultimate time to armchair quarterback the Star War franchise