Truly, though, at it's core, Dietary Law (Both Jewish and Islamic, which are very similar) represents early approaches to solving Public Health Issues more than anything else. My Admittedly Christian version of God doesn't care what you eat and don't eat; He created everything for Mankind to use to his greater glory. It's hard to work toward God's greater glory when you are laid out with febrile diarrhea, though.
Undercooked pork was giving people trichinosis, so the guys in the Big Black Hats (like in Jesus Christ Superstar) said "G*d doesn't want you to eat that". Because the people would listen if you invoked the almighty. The ONLY body of law was religious law, so that is where it had to be codified. Civil law and Religious law were one and the same in those days.
Same goes for Shigella, Hepatitis and all those other lovely diseases you can get from Shellgiraffe. Enough people get sick and here comes the Black Hats again "Hey, G*d say's don't eat that either". "And also, we'll standardize the way we kill things and also how we prepare them because G*d told us how and here's how to do it" (plus there will be less illness and the (sometimes sketchy) water supplies out here in Palestine will stay fresher longer)
Jewish Dietary Law was the first attempt on a community level to regulate food preparation and processing in order to minimize illness in the community. Of course, it came from the place where power resided at the time - Religious Authorities. It was very well though out and absolutely necessary for it's time. Modern farming and slaughtering practices make most of the restrictions unnecessary from a public health standpoint, but they represent thousands of years of religious tradition and they remain, particularly around the Holiest of Holidays, Passover.
Everything always comes back to Public Health for me. It's like I work seven days a week. Someone shoot me already.