Why "Hello World" as a first exercise?

[Richard Iswara <haujekchifan@gmail.com>]

Why is it most of the courses of introduction to programming or 
programming language use a "Hello World" kind of program as a demo or 
first exercise?
Why not do a proper input loop as a showcase or a first exercise? With 
an input loop procedure you get:
1. How to read and output an input.
2. Show the if-then-else structure.
3. Show the loop structure.
4. Show error messages and how to properly handle it.
5. On Ada in particular you are showing the type system.
6. If it is a subprogram then input loop shows how to do and call the 
subprograms.
And last but not least it teaches and reinforces to the student how to 
think about safety in programming.
So why a useless look at me, ain't I cool "Hello World"?

Sorry I had to vent after an unsatisfying exchange over at arstechnica.