I avoid eating "Blood" whether directly or indirectly, as via Meat from an Animal that hasn't been properly slaughtered ...
Please correct me if I'm mistaken, but isn't that a commandment that the Gospels retained?
If you look up the parallell in the Hebrew Bible (Leviticus 19:26, also Samuel I, 14:33), you'll see that this isn't only a dietary law, but a prohibition related to an idolatrous practice (Nachmanides commentary on Leviticus). It would make sense that early Christianity retained this, even after rejecting Torah ritual and dietary laws.
I know that J's Witnessess take this as a prohibition of accepting transfusions - something completely divorced from the sense of the Biblical text.
What do you think about religious food taboos or restrictions? Worthwhile, unnecessary or just plain silly?
"When threatened all beings fear for their lives; life is precious to all. When we put ourselves in the place of another, we do not kill, nor cause others to kill." Dammapada, verse 129
This verse resonates deeply with me; so deeply that I stopped eating meat. However, I live in an omnivorous society, and my practice is to enhance, not break, the bonds of community. Our 5th Precept is to abstain from abusing mind altering substances. When one of the roshis in our lineage was invited to parties, he'd put a little wine in his water; not because he liked watered-down wine, but so he would not be apart-from; set himself up as separate from the community of guests. Until relatively recently my tradition was almost exclusively monastic, and we have a tradition called Takuhatsu; mendicancy, where monks would beg for food donations in exchange for sutra recitations or prayers. Part of the Takuhatsu meal is the teaching to eat what has been offered without discrimination and with sincere gratitude. It is said that the Buddha died of eating tainted meat in this manner; he knew it was rancid, but accepted it gratefully and without giving rise to preferences or aversions.
Therefore, when I go to the grocers and buy food for myself, I practice the First Precept of not killing by not buying meat. When I'm a guest, I behave as a guest, and practice Takuhatsu; graciously accepting what's offered without discrimination and with sincere gratitude. Whether or not that appears to be "worthwhile, unnecessary or just plain silly" to others doesn't really matter; it's been a good spiritual practice for me.
Why would G-d care what we eat? The same reason He cares about any aspect of our lives, because He loves us and wants our best. Eating a part of life. It would be odd if He were concerned with other important areas of our lives, such as ethics, sex or health, but not be interested in our diets.
It is interesting that you readily accept a restriction against cannibalism but speak against diet restrictions of others.
You wrote, "A Jew can be thoroughly observant by keeping strict kosher at home and eating whatever s/he wishes outside the home. In fact, I know Jews who gorge on shrimp and lobster in restaurants, because they wouldn't dare bring a speck of either into their homes." This is incorrect. No observant Jew can do this. I'm sorry you have encountered some particular Jews that don't follow what their professed religion prescribes. However you should certainly not use a broad brush to tarnish all Jews with their pecadilloes. I promise not to do the same regarding Catholics.