It seems like Feige simply felt that Wright's script was too weird.
No it doesn't seem that way. Wright and co submitted several scipts, all of which were asked for rewrites, one of which got the go ahead to be given a release date.
The problem is, last year when the studio backed the "director's vision", these message boards went ape **** over changes to the Mandarin. There were people saying all kinds of terrible things about Feige over that because he backed Shane Black's vision for that character.
There are people to this day who call Iron Man 3 the worst comic book movie ever because of those changes, all due to Shane Black's vision. (FTR I am not one of them)
Now Wright is making radical changes to the characters, and it's OK because it's Edgar Wright, and how dare Feige and company interfere with his creative decisions, and it's Buster Keaton all over, etc., etc.
Seems like a crap load of hypocrisy, if you asked me.
And there are also people who defended the changes defiantly, just as now. Question was one of those, iirc. The lines are always split, and around here, more heavily and emotionally in favor of hate for the change.
I don't think they're split quite the same way because the Mandarin twist got it's shock value from marketing and fan (among others) expectations. So while the two days it took me to process the change and acknowledge how awesome it was happened after I formed my base reaction to IM3 (I found the twist off putting, but not as vitriolic as many did), the two days it took to see what excited Feige about Wrights' vision happened years ago.
On a side note, the more I think about it, the more awesome Trevor Slattery would have been if he'd be played by an actual Chinese descended actor.
And again, Feige and Marvel might have been totally in the right, but if they did the last minute stuff without warning as was rumored, that's messed up. Just because you are paying someone doesn't give you the moral authority to jerk them around. You have a responsibility to clearly communicate your desires and release the contractor as soon as you discover that you don't want what they're selling. You shouldn't retain people in the hopes that they will start selling something different because you can make their career or whatever. Any script revisions they wanted to mandate should have come with the notes from the first or second draft, not the last a few months before shooting.
Now there's a minority report. They may have only recently finished crafting the skeleton of Phase 3. As such, they wouldn't have known exactly what to mandate be in Ant-Man until a few months ago. So it's possible they didn't know exactly what effect such a mandate would have, but they've seen their mandates push other directors and actors away. So either they didn't care, or more likely, as businessmen, they were prepared to fall out with Wright at this time. How else could they be sure they could keep a soon coming release date if they did not have a plan?
It really does remind me of Joss Whedon and Wonder Woman. I honestly think Universal or Paramount should get the rights to Image and get Edgar Wright to run that universe.