I have no idea why they are doubling down on Master Chief's story. For me the best part about the previous story was what was happening around Chief. Meeting the Covenant, saving Keyes, blowing up Halo, Arbiter, Prophets, Flood, Ark....these are the things that pushed the story forward. Not the Master Chief. He is a vessel. But we'll probably get that Master Chief is related to Bornstellar and his evolution was unlocked or whatever happened in Halo 4 but was never mentioned in Halo 5...whoops.
Also, Hunt the Truth was a giant slap in the face to fans. None of that shit mattered in the game, and I doubt it ever will. Same with the Spartan Ops Janus Key bullshit.
They seem to start down a narrative path and then completely ignore it.
Get a good villain.
Kill people off left and right to add a sense of a threat. I mean in Halo 1 Keyes died at the end of the game. This showed the Flood weren't fucking around and they were trouble.
In Halo 2, Prophets were dying showing the sinister Truth trying to accomplish his goals. Elites were getting killed by their allied Brutes.
Halo 3, fan favorite Johnson dies, Miranda dies, Guilty Spark dies, Truth dies...what I'm trying to say is that there was always a sense of not knowing what could happen. I mean, at one point your allies with the Elites, and the next point you're teaming up with the Gravemind to kill Truth. That's a pretty cool experience. Anyway, you felt like you were in an actual war because you had victories and defeats. You cared about the side characters because they were decently developed and you had interactions with them in missions or cutscenes.
I could give two shits abut Locke, Lasky, Palmer, or any of the other new characters. Where is the character development? Who are the important players? The villains? Show me why I should care about these people.
My advice is to keep it simple stupid. Build the characters, establish the villain, get some major plot points you want to hit, add some stakes, and let us through Master Chief experience them. Don't make us have to read the comics, books, or other media to understand what is going on.