I just re-read Nathan Rabin's great AV Club interview with John Cleese from several years ago. One of many choice quotes:
AV CLUB: Have you written any scripts for yourself since Fierce Creatures?
JOHN CLEESE: No. I wrote a couple of scripts about three or four years ago, because I wanted to see if I could make a living writing scripts. And then I realized that you had to deal with the studios. No matter how much fun you had writing the script, at the end of the day, you were dealing with people who had no idea what they were doing, but had no idea that they had no idea what they were doing. It's terribly frustrating.
AVC: Which has to be all the more vexing, considering the incredible success of A Fish Called Wanda.
JC: Yes, but studio executives always treat people like me, and writers in particular, as though we live in some kind of ivory tower. And these executives think they know what audiences really like, despite the fact that I've spent my life in front of audiences. And the executives have never been in front of audiences, apart from sycophantic young junior executives who wouldn't dare not laugh at their jokes. So the whole idea that they have some kind of practical knowledge that I don't have is so ludicrous that it does not bear inspection. But they hang onto it. They hang onto a mystical belief that in the moment they inherited the biggest desk and office in their block, they also inherited an understanding of comedy. And it's absolutely insane, but they really do think that they understand it. And so they start telling you to do things which you know are wrong, and I don't know how you can write something that you know is wrong. I mean, what do you try, do you try to write it badly so it will be better? [Laughs.]