How many first impressions do you get?
That manuscript won't see the light of day if the publisher looks at your title: The Tail of My Life, by Tess Eloquence.
Have you ever rejected a job candidate because of his horrendous grammar or misspellings in his cover letter?
The art of language has certainly evolved but that doesn't mean we can't communicate with some style.
Think about it.
You may not have LOVED your high school English teacher but I'd bet you remember a few of the things he taught you. Mine instilled in me an appreciation of Shakespeare, poetry, vocabulary, and grammar; all the while gesticulating with hands (and spittle, to those unfortunate enough to be seated in the front three rows) and throwing chalk or other such smallish objects at those silly enough not to be paying attention.