Cover letters: why bother?

In my most recent trip through the slush pile, I was surprised to see so many submissions that didn't meet our requirements. I don't think it is unreasonable for Electric Spec to ask for some basics along with a story submission--like title, word count, and a short cover letter. When I get a blank e-mail, or even an e-mail that says only "Please consider the attached story," I'm attempted to reject the story outright for failure to follow our guidelines. In fact, if we start getting even more submissions than our current rate, I might just do so. Why? First, I'm hesitant to even open an attachment if I'm not clear on what it is. A blank e-mail isn't comforting. Second, we generally include the first name of the author and the name of the story in our submission responses, even if they are rejections. Sometimes I don't remember the title of the story or the first name of the author (e-mails don't always match) when I'm responding. I don't want to reopen the attachment to do that. Finally, if I have a word count up front, I have a better idea about how much time it will take me to consider the submission. Also, a missing word count makes me wonder if the story exceeds our guidelines. (Call me paranoid, but I've seen authors try to do this). 

I'm an author myself, and I know that it can be frustrating to send out so many submissions only to see a pile of rejections. But what I can't understand is why an author wouldn't take the time to write a three sentence cover letter along with his or her labor of love. It takes two minutes (max) and it gives you a little edge over those who don't bother.