I'm guessing it might have been a design decision due to the HUD. The Unreal engine supports any resolution that you throw at it normally and can maintain proper aspect ratio. The UT2K4 Mac edition actually has all the Apple widescreen resolutions in game, so there isn't even the need to muck with the ini files.

Oh, and if you ever work on an Unreal project again in the future, make sure to let them know they can remove the "Warfare" references. Was kinda funny to see some ini files with that name in them still.

That reminds me, any luck on the job hunt yet?