I think that you're missing a couple of the good points of HelloWorld.
1) It's small. It's about as small as you can get and still have some working code.
2) It provides feedback to the user. By actually printing something to the screen, the user -- a newbie by definition -- gets immediate feedback that s/he did something right.
3) It's friendly. It's hard not to feel good when you see the cheerful 'Hello World!' staring at you from the terminal window.
I agree with you that HelloWorld doesn't teach good OO practices, but I think the purpose of HelloWorld is to show the user that everything is set up correctly for some real programming to occur. It's more of a system check than a model of the RightThing.