Sure there is... It's the same reason that Spielberg edited out the firearms and replaced them with walkie-talkies in "E.T". Hint: the reason has two letters...Any idea why they aren't wearing guns? Seems an obvious miss for the theme of the costumes, so I'm guessing there's a reason.
("South Park" had a good response to Spielberg by producing an animated version of "Saving Private Ryan" in which the GI's came running off the landing craft carrying walkie-talkies instead of M1's.)