I hope you're right on the lighting bit, and am definitely encouraged by the rest of the design.
I think the harsh lighting in the pelican is partly to blame for how "clean" Chief looks- there's a couple moments later in the trailer, where you can see more of the realistic texturing and weathering to the armor (specifically the pauldrons). With how exceptionally good the materials otherwise look in the trailer (especially on the pilot's suit, and Chief's gloves), I'm not too worried about it. The tech demo trailer they showed last year also showed some really nice normal maps and parallax occlusion mapping, with a touch of washed out pastel colours - almost like watercolouring - that reminded me of Breath of the Wild a little bit.
Honestly, the armor design looks beautiful. Only concern is that the setting graphics looked too cartoonishYeah it felt just a tad too clean and new, other than that, I really liked the armour design
As for the armor design - I actually liked the redesign of the armor in Halo 4 on it's own merits, though it was definitely a departure from the other games. I also like the look of the quasi-classic armor for Infinite. My only issue with the Halo 4 redesign, was their nonsense non-explanation for it. Likewise, I hope they explain the return to a more classic look in this game, in a way that doesn't involve O'Connor's famed "nanobots".
TBH, I think I'm just unhappy with the current state of Halo ATM and that's causing me to have an unfairly negative outlook on future titles.
When they initially show the new armor (when he's being moved with the winch and dropped), he essentially has a flood light pointed directly at him, blowing out any details on the surface of his armor. When he walks over to the pilot later on, you can see the weathering and texturing on his pauldrons and chest piece more clearly. It looks good (especially on a 4K screen), and I doubt that it's like 343i will have "forgotten" to add detail to his armor or something in development.
As for the state of Halo, this is actually the best I've felt about it since the pre-Halo 4 days. 343i are giving the impression that they've learned the right lessons from the reception of Halo 4 and 5. The new engine looks gorgeous, as does the aesthetic redesign, and 343i are being pleasantly transparent about their vision, as well as saying all the right things. Just admitting that Halo 5's story wasn't the quality it needed to be, speaks volumes to the idea that they "get it". Halo 5 ended with a pretty decent Metacritic score, and it would have been easy for them to decide that they were on the right track, and it was just the community being fickle, or whatever.
Honestly, my only fear now is that they listen TOO MUCH to people like HiddenXperia, and the other diehards who want everything to look and feel "classic" forever, which could easily result in stagnation for the series.
But right now? I'm very optimistic about Infinite, and MCC PC.