I'm not so sure I'd go so far as to say it's dead. There were a few apps open for other carriers recently that had an upload option for cover letters, etc.

Now, if you were going to a job fair and talking to the Atlas reps, giving them your resume, your PAQ, an internal rec letter if you have one, AND a cover letter probably wouldn't be a mistake.

But it's been covered in the thread multiple times, as far as the email submission goes, not necessary.