Please explain how you know ego was the reason for [changing a story]
It's a valid counterpoint that maybe the writer is not in control of what they are being asked to write, so they could be excused from ego, but at either the writing level or somewhere up the decision chain, someone has decided on a "better" way to tell it. It's fair enough to assume that the creatives in power have egos, and use them, or they wouldn't be where they are. This can come off as knowing better than the author how to tell the author's story. Choose your word: arrogance, self-assured, hubris, ego - it's all quite common. And of course, as they would tell us, if you don't like this opinion, don't buy it.