If you're going to use an existing product's brand recognition instead of coming up with your own ideas, you need to be prepared for the criticism that comes with that.

And it's not particular harsh to say "turning a recognizable sci-fi setting into a Wal-Mart version of whatever other sci-fi property was popular the year before it was made" is hacky storytelling.

The Halo show never needed to adapt the stories of the games. But it did need to adapt a story that would actually be told in that setting. There's a lot of expanded material to draw from and help fill out a political intrigue story if they wanted to do that. There's a lot of stories to be told about the war crimes ONI were committing even BEFORE the Covenant showed up, and the unethical experiments Halsey performed on children, and how even though those things turned out all right in the end - when an unpredictable alien threat made the super soldiers they created to put down riots and rebellions the last hope for humanity - they are awful, awful people.

But they were too lazy to do any research that would help them actually write a story like that (one which wouldn't involve the Master Chief at all, which could have been an even greater boon for flexibility in writing), and too incompetent to actually make an engaging one on their own.

Fandom doesn't have "an obsession with xeroxing", faceless corporations have an obsession with making money off the backs of others without actually needing to put in any effort themselves. Taking an existing property and slapping it as a loose coat of paint on generic sci-fi slop completely fits the bill.

If you can't tell a better story than the property you're adapting, stick to the ****ing source material. And chances are, if you're adapting a story that you're not a fan of to begin with, you're a ham-and-egger. Stop trying to stroke your own ego by saying "I could do better than this insanely popular story everyone likes" (looking at you too, Wheel of Time showrunners).