When I turn hyphenation on I expect to see hyphenation. There may be sound reasons why this cannot work as expected, e.g. because the language setting does not support hyphenation. In this case the user interface should give some feedback that explains the cause of the problem ("Your language setting '[None]' does not support hyphenation.") and provides some hints what to do about ("You can change the language setting ... there ...").

How to reproduce:
In Calc, open the "Format Cells" dialogue either using Format -> Cells (starting from the main menu) or pressing CTRL+1. Open the "Font" tab and set the language to "[None]". Open the "Alignment" tab. Check "Wrap text automatically" and then "Hyphenation active". 

Current behaviour:
It is possible to activate these controls without any further feedback despite the fact that hyphenation cannot work with the given language setting.

Expected behaviour: 
The UI provides easy access to the information that is necessary to assess if checking the "Hyphenation active" control will work as expected. Maybe just add a label near the "Hyphenation active" check box that displays the current language. As the language might not be what the user expected and not all languages support hyphenation, there should be some hints pointing to the location where the language setting can be changed and an information that tells the user if hyphenation is supported or not.

For background information see bug 79027

Observed with LibreOffice 4.3.4.1 and Windows 7