I agree, but honestly, do you think a game as simple as CE would do well these days in terms of the general populous?
Sure, you and I would love it (as would most of HaloGaf). It would be the back-to-the-roots Halo game that brought us all together to begin with. Splash on some new graphics, add a couple new gametypes here and there and be done with it.
I don't think the rest of the world of young kids out there who have come to expect huge marketing campaigns, 40 different game modes, 8 billions pieces of customizable armor/weapons/etc.., huge single-player components, and all the extra bells and whistles that they justify the reason they're (their parents) dropping $60 on a game would be over-thrilled.
I don't want it to sound like I'm speaking on their behalf because I am on their side. I'm not. But I understand it. It's easier to sell a game when you can throw a book of "new features, tons of maps, 40 hour campaigns, customization to the moon, etc" at the consumer.