I daresay most modern educated poeple who'd thought about it at all would agree with you about the origins of the Laws of Kashrut (that is, what is and isn't kosher). For instance, the prohibition against seafood was likely for the same hygenic reasons as pork.

There is, however, another dimension, which also relates to ancient versus modern practices: the behavior of the animals in question, and what they eat. Pigs in their natural state will eat anything, including their own feces. I suspect it was their observable behavior which earned them the label "unclean", rather than a correlation between undercooked pork and trichinosis.

Stripped of their florid language, kashrut laws can be reduced to three basic principles: no blood; no bottom-feeders; humane treatment. Thus: no predators (eaters of blood), whether land animal or bird. Sharks and dolphins are eliminated as predators, and shellfish as bottom-feeders, under the "fish must have scales" rule. "Bottom-feeders" also includes reptiles, as well as pigs.

I know plenty of modern Jews who eat pork and/or shellfish -- they have drawn their own conclusions about the relevance of kashrut to modern times. There are plenty more (myself among them) who choose to observe the "no pork" rule for its symbolism, as a connection to their heritage.

By the way, it's not just Jews and Muslims. Strict Seventh-Day Adventists keep kosher, too.