You mean Fireteam Osiris who are basically all new Spartan recruits and have barely worked together? I'm not implying that Spartan-III's are better either. But to say they're in another league when Noble Team was highly regarded for basically coming out of suicide missions all the time? Carter was also one of the highest ranking Spartans.
My point is, Noble Team got picked off one by one, we see Red Team suffering in the recent Halo Wars 2 trailer, and we've seen that propaganda aside, Spartans aren't invincible, even the 'legendary Master Chief'. How are 4 Spartans going to drop in between Covenant cruisers, with Wraiths on the ground, Phantoms flying overhead with Forerunners and Elites and all kinds of enemies and just run and gun like it's nothing? It's a bit too far left field for my taste. Obviously just a cinematic, but let's be realistic. Spartan-IV may have new fangled gen2 armor, and deus ex machina augmentation to make them go toe to toe with Spartan-II but they're basically regular recruits now.
I loved the cinematic and gets me excited for campaign. I simply don't necessarily like the superman style lack of danger.