Auhtors, why...

I let out a breath I didn't realize I was holding...

What's up with that sentence. Authors seem to think it's magical and write it in every. single. book. There are variations of course, and of which the most obscure one was "He let out a breath I didn't realize he was holding". Now that doen't sound that weird, but the thing is the author used the same line, not twice nor thrice, but four times during a small time span.
         
So I started thinking that there are things like these which we don't even notice anymore. They come and go as a norm and I don't think this should be one.

Another example is from movies and tv shows. How and why is one always in the middle of the elevator when the doors close, so we see your nose for the longest?

Love at first sight. I just don't get it.
Then again if two people hate each other why should they end up together? There is a thing called friends and I like reading about them more than love triangles...

I'm sure there are people with different opinions, but these are just some of mine.