[gsivil]

I think your point is valid and of course interesting for programmers, but KR's "Hello, world!" is still relevant for students and novices. Maybe reading/writing on a file would be more useful nowadays, since it does not demand knowledge of algorithms.

[ollysb]

A large part of the value of a hello world is to check that you've actually installed the language correctly and can compile/run code. Printing hello world is just the simplest way of proving it.

[ctdonath]

It is very relevant for total novices. When someone has no concept about programming, this is the fastest way to "here are the barest basics, and you have already written a program."

Quick sort means nothing to someone who does not yet grok compiling and output, much less sorting as an algorithmic process.

Question isn't whether "hello world" is obsolete, it's the level of knowledge of the author. A rank noob needs to see the simplest possible program, not the highest density functionality.