Hold on let me give you the generic response: IT'S NOT HOW TRUE SPARTANS ACT IT'S BAD. SPARTAN IV's ARE BAD AND SHOULD DIE!
Now let me give you my response: If this is a war game simulation, and please pay attention to the word "game", and the Spartan IV's are human, this is common human nature. To act like this during an invasion or after a real firefight then yeah it'd be a little stupid, but this is a competitive game with friends (the Spartan IVs are depicted as a team so they have to get along and be friends somewhat) so it is normal human nature.
I feel people have more of a problem with it because when most people think of Spartans they think of the S-II variety. But there's an obvious difference between S-IIs and S-IVs and they are numbered different for a reason. Not every Spartan has to act like a reserve Spartan II like Master Chief.
My opinion on the animations is that they're a nice little addition that let's you see your teammates before a game, but even if I didn't like them I don't care enough to complain about that. It has little effect on the gameplay which is the most important thing people should care about when it comes to a Multiplayer beta. They can stay or go, but they're still there so we'll see what "reduced dudebro" means in regards to the animations.
I also like what peanut said if they stay.