What’s so wrong about using cliches?

http://theeditorsblog.net/2011/01/26/cliches-are-they-really-that-bad/
Every time we look at a person or a tree we see a different vision.But to  simplify life we tend to create a fixed image of them in our mind and instead of seeing the person we see this image.I know that is why sometimes people don’t notice when someone else is upset or happy.
The funniest example is from my own life.I used to be extremely thin until I got married.Then I became normal.Unfortunately owing to health issues I then got  much bigger.I met a former colleague in the town.She always did have a sharp tongue.When we were discussing clothes she said something nasty to me based on the fact that she believed I was still very thin.So she wasn’t seeing me.
If we can see better we can describe better.But that may mean using new metaphors or  other words/sentences.Is it too demanding? If you want to write better you can’t rely on using second hand phrases.They are a way of avoiding seeing.
Even in oral communication we need to avoid them if possible because they are boring.But they are a short cut so that is why we do it.