This is something I really hate as an artist myself.
Two weird opinion camps on peace of entertainment.
1) I would've write better thing than it's own author.... That's not only disrespectful, but also bigheaded. If so, why aren't you doing better stuff than him?
Answer is simple, because that person didn't got into the industry. Because that is something that involves hard work and lot of luck. Sometimes both, sometimes only one of it.
Akira Toriyama did. Person who criticizes the work, didn't, he only builds on fruits of someone else's work.
Tough I approve of constructive criticism.
2) You can't criticize the movie, if you are not involved succesfully in the industry.
That's also bulshit. The reason behind doing this creative work is that it is for the people that enjoy it - or for self realisation of the artist.
Myself, I am doing music for myself, because it is fun and I don't care what anyone else thinks, tough I had a full club this saturday, LOL

But I appreciate constructive criticism, if I am doing something wrong, or something is off from the technological point of view or consistency.
But what I ignore is thing like: ''Your music is shit, because I don't like it.'' Yeah, then thanks for your opinion man, you can p**s off and find yourself what you like.
Or should the artist think to himself: ''Ah yes, should I make something that I don't like, but it will please the majority of people or this angry guy down there,
so I will make ton of money and lose my own soul and creativity?'' Yeah, definitely!
I really appreciate and like even more, that Mr. Toriyama had such luck with his disctinctive style and attitude, to create one of the biggest franchises
that made him a lot of money, but he came back and doesn't care exactly, what the fans want or created before in fanfiction (Said so in interview).
I really like that story of him not liking the BoG script, so he went in to change it. He still pulls the ideas on the go from nowhere, like before when he did the manga.
I wonder what would happen without the editors in the manga run.
If majority of fans like the new movies, than it's great. If not, then the movies will have different fans that like it.
In the end, it doesn't matter, because that stuff is made for entertainment. No need for strong arguments and disrespect.
I have one thing in the end and it is not meant negatively for guys, who claim that they will make a better movie.
If you are really strong in writing or storytelling, place your bet in that and try to work on that, otherwise it will be a pitty if someone even didn't try to go out and show his or hers creativity.
Without the guts, lot of possible good artists and creators are buried in themselves and no one knows.