That may be the core of the whole argument. It reminds me of George Macdonald Fraser's WW2 memoirs, in which he and a bunch of other conscripts fight the Imphal-Kohima campaign. The fighting is savage and the enemy vicious, but the book is frequently quite funny. The soldiers joke and bicker continuously, do silly things and are very human, but are also very tough and dangerous when the fighting comes (and hence win).
What doesn't happen are passionate speeches about liberty, silent grim-jawed staring into the distance, sobbing promises of vengeance when anyone dies or any of the other cliched things "warriors" are supposed to do. No doubt this will upset people who go all giggly about Sparta (or, er, certain less salubrious armies), but it feels much more realistic. So, in short, there is more to depicting people in tough situations than the Gears of War trailer might have us believe...