Here are five common reasons companies use these maddeningly vague rejection letters:
1. They're afraid of being sued. Many companies are under orders from their lawyers not to get into the reasons for job rejections, in case a candidate doesn't like the explanation and decides the "real" reason must be discriminatory.
2. They don't want to deal with candidates who get angry and try to debate the decision. Everyone who does hiring has stories about rejected candidates who wouldn't stop arguing the decision, and some who got so angry that they were scary.
3. The reason you were rejected is an awkward one. It's one thing to explain that you needed stronger writing skills or more bookkeeping experience. But most people don't want to have to explain that you seemed like a jerk, or crazy, or not very bright.
4. They don't have time. Offering up thoughtful feedback to every rejected candidate could be a job unto itself, and ultimately that's not what hiring staffers are there for.
5. They did tell you the reason and you don't believe them. A lot of times "you were really great, but someone else was a better fit," is just the truth.
All that said, you have nothing to lose by writing back and asking for feedback after you get that vague rejection E-mail. If you do it well (politely, non-defensively) and you have an interviewer who wants to help, you just may get some helpful advice.
Alison Green is the author of Managing to Change the World: The Nonprofit Leader's Guide to Getting Results. She is chief of staff for the Marijuana Policy Project, a nonprofit lobbying organization, where she oversees day-to-day management of the staff as well as hiring, firing, and staff development. Her writings have been published in the Washington Post, the New York Times, Maxim, and dozens of other newspapers. She blogs at Ask a Manager.