My guess is that because they threw so much money at this, they also put too many cooks in the kitchen. You're gonna end up killing all creativity if it has to get rubber-stamped by a long line of "producers".

Because too much of the money goes to the intellectual property owner as rent.

And also, prequel/sequel stuff that was not originally mapped out by the author is usually crap.

Absolutely has nothing to do with the IP owner.

That much money (as well as being tied to a big name like Amazon) attracts the antithesis of creativity, where everything becomes ‘plastic’ (someone above called it a ‘wax museum’ which is a good way to put it) and means anything remotely controversial or original will be killed dead.

I don't think thats the case, its this forcing of current US politics into writing that doesn't have the skill to include it in a seamless way to be compatible with world building and storytelling. Also the CGI that's really the highest point for a lot of people seems really bad to me, everything looks so plastic ...