Typically when Marines disembark from the AAV after an ADDRAC has been given, the AAV forms the base of fire at 12 o'clock. Not only does this provide the obvious firepower, but it also helps the Marines orient to the target when they come out of the back. If the squad leader has his crap together, he should direct his fire teams to split left and right of the AAV. It would be absurd to discharge personnel out of the back of the AAV into oncoming fire. It's the job of the AAV crew to ensure that doesn't happen.
If the AAV is discharging personnel under conditions that do not involve incoming fire, then typically the situation will dictate how the AAV can orientate itself and the personnel can exit.
And to answer the OP's question, yes it is just Hollywood being Hollywood.