You know, looking at reports, I definitely think that it was an idea that was executed badly for reasons that were not just because of the open world concept. Maybe if they had developed a better engine that offloaded the tech debt they had for so long, or if their hiring practices weren't on 18 month contracts, or if they had a better vision in the game direction, etc., the game wouldn't have ended up in this place, and the open world might have worked out, and they didn't have to cut so much from the game. But asking what ifs is no use, the game in the end still left much to be desired.

I share the same opinion as you, that the story in Infinite did not really satisfy me. But it still got some positive responses to it and some people liked it, and I'm happy for them. The open world concept in Infinite is inspired by the semi open world map in Halo 1 like Arriving on Halo, art direction is inspired by Bungie Halo but much more polished, and lots of story pieces are referenced from old Halo games or extended universe materials. So saying that the devs did not do their homework is kinda unfair, imo. For that, the Halo TV show by Paramount takes the crown of disregarding original materials (or even the basic concept, even).

There's a pretty good video essay on YT that goes more in depth into what 343 did right for Infinite's story, I'll link it here. Although 1 hour long, I highly recommend giving it a watch. His Halo 4 retrospective video is pretty good too.

I definitely still prefer a concentrated and linear story line, though. Like watching a movie or a TV show, I want to be on the ride that the game designers intended. Not saying that open world games can't deliver the same experience, but linear games have the advantage of having more control of the story beats in the game. I guess we'll see what the new leadership would bring.