Text Stat can be useful for quite a few users, let me give you one example. You can check out word repetitions with it easily. Say you are writing an article for a website and want to make it keyword rich, you do not want to add your main keyword to often, just often enough and use synonyms when the limit is reached.

You can check your text and get figures on how many times you have been using the main keyword. It still requires some quick calculation on your part about keyword density. If the figures are to high you simply exchange some of them with synonyms.

Another option would be to have a quick option to check if the text meets certain requirements such as a specific word count or amount of paragraphs.