A vocabulary software may not be the greatest thing for developing writing skills. Used well, however, it can help you acquire a facility for language that can translate well into your future writing endeavors.
Vocabulary programs do one primary thing: they aid in your learning of new words and phrases. The more items you learn, the broader your stock of the language gets and that growth can help your writing in many ways.
When you have a broad vocabulary, it becomes easier to express yourself in writing. With access to more words at your disposal, you no longer have to consult a thesaurus for every other sentence you write — you’ll have exactly what you need to express a thought precisely in your head.
When you have a strong vocabulary, you get a more accurate sense of whether a word is appropriate to use or not. Beyond dictionary definitions, words have implications built up over years of use, after all. Regular work with a vocabulary software can help become more sensitive to those differences.
Simply put: the better your vocabulary, the greater facility you have for the language. You can speak it better, write it better and understand it better, and all those things play a part in how well you express yourself in writing.