Additional kudos to Astro, who chimed in on the discussion with an addy to an online version of the article mentioned below. While most of it is on other topics (still a good read), Halo does make a brief appearance towards the bottom:

But just as all movies, books or paintings aren't the same, neither are all games, and some require as much realism as possible. It lets us tell a better story, says veteran designer Jason Jones, demonstrating the spectacular blend of shooting, flying and driving in Bungie's upcoming PC/Mac game Halo. Shadows stretch and contract as he speeds over uneven terrain, and when he slams the brakes, the driver whiplashes forward and back, and the level of detail just pulls you in. [With 2-D graphics] there's no way you could tell a story like this, he says. We're going to give people as few excuses as we can to realize that they're playing a game. In other words, Game Over just took on a whole new meaning.

You can't help but love that design philosophy, eh? Better set aside some time for this one in advance... a few months should do the trick.