With all your helpful feedback it was easy to determine the most anticipated feature I would implement next: Automatically enabled word-wrap!
The latest version (v0.1.1) of my Eclipse Word-Wrap plugin offers the possibility to automatically enable the word-wrap when certain file types are opened. (By the way: You can take a look at the source code at github if you like to.)
The filename extensions can be configured in the Eclipse preference pane "Word Wrap":
You can add or remove file extensions to enable the auto word-wrap only for certain file types. After adding a new entry to the list word-wrapping is automatically activated when a file with the specified extension is opened. Of course it is still possible to toggle the word-wrapping for each editor separately.
If you have any suggestions or problems please don't hesitate to contact me.