First appearance: As James Rhodes, Iron Man #118 (1979); as War Machine, Iron Man #282 (1992)
Remember how excited everyone was when it was revealed that Don Cheadle would play War Machine in Iron Man 2? Well, do you also remember how disappointed everyone became when Cheadle basically drained all of the life out of the movie by being completely outmatched by Robert Downey Jr.?
Now imagine that type of sleepwalking performance by Cheadle for an entire solo movie without the humor and sarcastic one-liners by Downey propping him up. Not only would the movie pale in comparison to the original Iron Man, but it would probably drop below The Incredible Hulk and Captain America: The First Avenger as well.
In terms of appearance and powers, War Machine is just too similar to Iron Man to make for a truly unique story. Plus, the character of James Rhodes does little to stand out on his own. Marvel has been doing a good job with its properties so far, but the company can’t think that every one of its properties is ready for its close up.