A cover letter became a standard in recruitment process. When I read papers from candidates I’m quite sure that for them, the cover letter is much harder to write than the cv. At least for those who don’t send a single version to all companies they’re applying for. I have an advice for you – if you want to send me a copy of your universal resume, don’t bother and send none. You’ll save your time and mine. But when you want to earn some points on papers evaluation stage, invest some time and write personal cover letter addressed to me and my company. You have some details about the company (web site) and job (job offer). You probably have some ideas what you’d do on the position. Your cover letter should address all those information. If your profile and experience can’t cover any of them, think twice if the job is exactly what you’re ready to do. And then think twice if you aren’t accidentally wasting your time.