How are they portraying vehicles as a major part of the game? They're right in the background, you don't see a clear shot of any of them, and the *focus* of the ad is on the two characters in the foreground shooting at each other.
What do you want them to do, put the vehicles in caged boxes with "DO NOT TOUCH" signs on them to make it clear that they're less important? The vehicles are IN the game, so of course they're gonna put them somewhere. It's an ad. It's designed to make everything in the game look exciting, including the vehicles which ARE going to attract UT2004 players. You act like they DON'T want to do that.
The fact of the matter is that the ad looks exciting. If you show that to somebody who's totally ignorant to Tribes, he'll probably go "Dude, awesome." and try it. Now, just to flip it back to the classic argument at the moment, if you showed him the box art he'd go "Wtf, lame." and look at you funny. Then pick up HL2.