In a recent talk, Joe Welinske demonstrated the example of improving a mobile application by changing just one word on the user interface. As he explains it, the value of user assistance professionals isn't that we can choose words, but that we know what the right words are to choose. Good technical communication is about knowing what the right words are, and then using then clearly and concisely.
Here's a sample of some work I did recently. The original I found wordy, to say the least:
Developing good user assistance means identifying what information users need and making that information easy to find. In this sample, I highlighted the important points. The original author buried the important information in a mass of words.
Here's what I changed it to:
The best writing, like the best coding coding, is efficient. In this case, I cut the words by a good two-thirds and made the concept clear and easy to understand.