Why do so many big budget movies end up full of rookie filmaking/writing mistakes?

Do you have a better example of mistakes? I haven’t seen this movie nor heard enough about it to know how apt your criticisms are. I wouldn’t use the word “mistake” for deliberate deviations from a formula.

It’s really not like a role playing character sheet, where putting emphasis on one thing is independent of putting emphasis on another thing.

You don’t get a good script by spending more money on writers. I bet these trainwreck movies with seven different writing teams all doing different rewrites spent a ton of money on writers, but that’s not the problem. You get a good script by hiring a good writer and letting them make the decisions.

But that script might not maximize the use of cool gadgets that will sell more action figures. Or it might not tie in to the multi-year multi-movie arc that the studio is planning. Or it might not have a shooting schedule that’s compatible with the seven different name actors who all have their own lives and incentives and carefully negotiated contracts. Or any of a thousand different things.

So ultimately, the writer doesn’t get to make the call on what happens in the movie. The writer is given a bunch of constraints and does the best they can, but if the constraints are too great then the best they can is not really that good, and the problem isn’t that the studio didn’t put enough money or effort into writing, it’s that “make a good movie” is pretty far down on the priority list.

It would take a 34 minute video to highlight all the editing mistakes. The narrative is so disjointed it’s almost impossible to follow. This is despite there being a TON of clunky exposition. Most characters get two extensive introductory scenes, grinding everything to a halt for some half-baked, micro music videos. One antagonist gets a lot of screen time in the first half of the movie, but then is never shown or mentioned again. The few squad members with internal and external goals (beyond the imposed mission) are laughably shallow.

Deliberate deviations from storytelling formulae are fine, but you have to know why those rules exist before you break them. I think they were going for non-linear, but all the flashbacks and cutaways didn’t flow in ANY way. They weren’t keeping select information from the audience, nor were they giving away extra info, either.

I believe that the answers to all of your questions can be found in a two-part YouTube video, taken from a Q&A session with Kevin Smith.