I know, I love the Ultimates, but I'd really rather the movie be about the team dynamic as a whole and not waste too much time focusing on specific people. They can still have him play off of the rest of the team's modern views of the world after they establish him fully as a fish out of water in his own movie.
Yeah, they should totally make the WW2 portion of Captain America as stylized and propaganda-esque as possible, actually, since that's what the comics were. Make it "BUY WAR BONDS"-y as hell, completely in the style of the 30s/40s.