This is exactly why 343 tried to branch off of Chief.
In this huge and wonderful universe known as Halo, you can't keep relying on one character to do literally everything and drive the story. There are plenty of other cool people in this universe, and I am glad that we got to see some.
I perfectly agree that the Halo Universe is big and should be thoroughly explored beyond the mainline games. But handle those outside stories as Halo: XYZ, aka Halo: ODST. Let the numbered games follow Master Chief, as it's been his story for the longest (and everyone except you clamored to play Chief again throughout 5). Halo 5, to put it bluntly, should've been called Halo: Locke or some variation of that. I'm not saying anything that hasn't been said countless times in this thread, but playing primarily as Jameson was lame on so many levels.
Hell, spin off the series into another subseries, like Halo Wars.
The podcast Hunt the Truth setup this really outside image of the Chief and him going rogue. Yet we saw just a hint of that in 5. And I can't be the only one that felt Master Chief was awfully out of character in Halo 5. For one, he punches Locke first, in the face of reason (ha!). And his dialogue definitely felt like it was written by someone who doesn't quite understand who the Master Chief has been all of these games. "Like hell you will." That is so antagonistic, I can't think of any other time the Master Chief was that much of an asshole to anyone throughout the series. Get outta here with that shit, 343.
I had high hopes for Halo 5, I really did. 343 really let me down. Again. I have zero faith Halo 6 will be any better than its previous two entries. I'll still buy it, because Halo is one of my most beloved franchises in all of video games, but I'll be setting the bar very very low.