"It looks interesting man, but it doesn't really appeal to me. I get my nutrition from fresh, raw organic produce, meats, etc. and it's working great for me!"
It's certainly possible that there are other approaches that work well. I don't see why eating 8 meals a day should be the only way.
"Why is that then? I've heard quite a few people take the complete opposite extreme and recommend drinking a gallon of milk a day, which contains a huge amount of calories."
Typically those doing this are looking to put on tons of size. Mark Rippetoe suggests this in his program Starting Strength.
I don't think drinking a gallon of milk would be considered a basic diet guideline :)
I do the Zone -- it's a very sensible, straight forward and simple program. I do it Mon-Fri and take the weekends off. On weekends I eat healthy, but don't measure anything and if I want to treat myself to something, I do it and don't worry. Doing this for about 6 weeks now, I leaned out quite a bit and am down 9lbs. I did it strictly for performance reasons, not aesthetic reasons, and am very pleased with being leaner and lighter and not losing any energy or strength that I've noticed.