Have you have ever had someone say to you - "Hey its great that you will be seeing X next Monday, say my Hello "? Now really, what good does this do? What is the noble idea of asking me to say Hello on this person's behalf? Why cant they muster up the courage, the time, the motivation, the dedication or whatever it is that takes for him/herself (in most cases its a HER) and say Hello themselves? Some people do not stop at just asking you to be their "hello" carriers, but they ask feedback when you see them next time - "So did you say my Hello to Jack when you met him?"
Another such meaningless phrase that the general populace uses liberally:
"Good for you" - the only thing I can think of when someone says this is "Thank you but F%&k you."