As stated, not everyone plays Halo exclusively over XBConnect or one of the other services. For instance, sometimes I have a small LAN party at my home, but the problem is, there's no internet service there. Hell, I talk on these boards mainly from the library or my brother's home.
Back to the point... Halo runs fine on a normal LAN with, say, 2 other XBoxes, when internet access is nowhere in sight. It'd be good to be able to download the patching engine so I don't have to run back to my brother's place every time I want to, say, make a patch for the Scorpion to fly, too, or to patch a different level.