Parshat Shemini, 7th Portion, Leviticus 11:33-47, April 2, 2016

This seems to be a good discussion of the different  theories about the kosher diet. Different reasons are put forth and then sometimes dismissed. 

http://www.jewishencyclopedia.com/articles/4408-clean-and-unclean-animals

In Buddhism we talk about not being attached to our preferences. In Judaism I get a sense that the opposite is true—that we are encourage to be attached.

There are many examples in the Talmud how what appeared to be black and white ended up to be colored with 50 shades of gray. 

This gives the Jew a lot of autonomy. They are told exactly what to do except if they are met with an exceptional situation, which I suspect is a frequent case.

I understand too that clean and unclean are not about sin, but whether a person is ready for the temple and Torah study. We take a shower, but does that really make us clean? What about apologizing to people that we have harmed? How about thanking people who help us? And the story goes on and on. I heard once that your closet and the trunk of your car are a portrait of who you are. Are they clean? Are they ready to study the Torah or to pray?

To me, this is a mindfulness practice. We do this, but not that. We eat this, but not then. And we need to wake up and watch our actions. “The unclean animals,” says Arama, “cause coarseness and dulness of the soul.” This quote was from the article link above.

P.S. Perhaps all the exceptions in the Talmud suggest that one should not be attached to their preferences. For example, the bitter herb to eat for Passover should be lettuce (which goes from sweet to bitter as it ages like the Jews' experience was in Egypt). But if lettuce is not available then many other herbs will suffice... and today, many use horseradish, which isn't approved. The important thing is to engage in the practice, even if you can't have it the “perfect” way.