Well the one problem with Rodey is, he's got his orders to obey. I would think War Machine was more than likely protecting the President and couldn't help the Avengers.
It's sort of the reason U.S.Agent came about. The military realises Steve is technically still THEIRS to order around.
Originally Posted by InternetPeople
I didn't say War Machine would break the plot, though a too powerful military showing up easily could. I do think they would be extremely powerful against the lightly-armored Chitauri invasion. Think IM2 when Tony and Rhodey just stood there blasting the HammerDrones, that's what War Machine would do, just stand and be a turret. That's also what I think the military would do, but way more of it and from every possible direction.
I think by including the military, they would have either been an overwhelming force or a bunch of bungling idiots. I think War Machine would have been very effective sitting in an intersection or rooftop, probably too effective. In this film, I think he would be Hawkeye with guns, but Hawkeye's bow and arrows are much cooler than a gun and his limitations are much more fun to play with.
Would a dude sitting on a roof with a rifle picking off Chitauri have been fun? Not really. But a dude with a bow and arrows that do cool stuff, hellz yeah! That's fun.