I'll come right to the point. I dislike exclamation marks. I avoid them. One exclamation mark feels loud, two or more even threatening. If you use the right word, you won't need one. "You're an idiot." That will do.
Terry Pratchet says: "Five exclamation marks, the sure sign of an insane mind." I cannot agree more.
Don't get me wrong. I do not want to abolish the exclamation mark. We need it. According to the Duden, the dictionary of the German language, we may use it with commands, requests, or exclamations:
"Give it to me!"
"But I want ice cream!"
We also like to use the exclamation mark with allegations and insults. Latter are common in social networks and online newspaper comments. There, the commentators like to fill entire lines with exclamation marks. They are also a favorite of the tabloid press. Just look at those headlines.
For those who love series of exclamation marks, I recommend the Ausrufezeichen-Vernichter. It's in German and translates into something like "exclamation mark killer": http://www.buchstabendose.de/dosen/ausrufezeichen.php. Try it anyway, it's multilingual.
In technical documentation, the exclamation mark makes sense. For example, we use it to indicate potential hazard:
"WARNING! Risk of burns! Do not touch the screen."
I suppose I could write a lot about warnings in technical documentation now. But I won't. I just wanted to say something about unnecessary exclamation marks!