efficient conversations

Why do we assume that when people ask us to repeat ourselves, we think that they only missed the last part of the sentence? That's why this kind of conversation happens all the time:

Friend: "I saw Avatar the other day and it was so amazing!"
Me: "Sorry, what'd you say?"
Friend: "It was amazing!"
Me: "What was amazing?"
Friend: "Avatar!"

He could've just repeated the entire sentence, and we would've saved an entire two lines of dialog. Here's another more annoying example:

Friend: "I was in New York last weekend and we went to this fabulous restaurant called Balthazar."
Me: "Sorry, what'd you say?"
Friend: "Balthazar!"
Me: "Huh? What's that?"
Friend: "It's a restaurant!"
Me: "Okay..." [awkward silence] "Why are you talking about it?"
Friend: "I went there last weekend!"
Me: "Oh, cool." [awkward silence] "How was it?"
Friend: "It was great!"

Me: not interested anymore.

See how much time and awkward silences could've been saved if she'd just repeated the entire sentence after I said "What?" And in this situation, I didn't even get to find out that she was in New York the past weekend!

Wouldn't this have been so much easier?

Friend: "I was in New York last weekend and we went to this fabulous restaurant called Balthazar."
Me: "Sorry, what'd you say?"
Friend: "I was in New York last weekend and we went to this fabulous restaurant called Balthazar!"

Me: "Awesome!"

So I'd like to propose that whenever anyone asks us to repeat ourselves, we repeat the entire sentence we just said, or at least a summary of it. You might think that it's a bother and would take more time than is necessary, but I disagree completely. Efficiency is a value that belongs in all arenas of life.

Does this annoy you as much as it annoys me?