FAQ on Pi-Calculus (2002) [pdf]
cs.cmu.edu
cs.cmu.edu
I'd love to be proven wrong, but it seems to be a niche for a community of researchers to publish useless technical papers. At least, they should devote their energy to try to apply their results to solve real problems.
I'd be wary of claiming that something isn't practical just because it hasn't escaped the academic world yet. Bringing research stuff to "real world" is a hard skill, and in my opinion of a very high value.
You might instead have said this about any researcher in abstract mathematics, computer science, and even theoretical physics.
Some people enjoy working directly on "real problems", and that is fine. But plenty of other people enjoy working simply to push the frontier of our knowledge, and that's also fine.
pi-calculus and lambda calculus are both theoretical frameworks, engineered for clarity of notation and thought, in order to reason better about theoretical problems in computation. Neither of them were designed to be practical programming tools, and their merit does not rest on whether they happen to inspire such tools.