I was talking to a hiring manager recently, and she said, “I'd like to get another developer just like Stan.” Well, Stan is a good guy and a talented developer, but why look for someone just like him? The manager explained, “I'm staffing a particularly risky project and with someone just like Stan, I know we'll do well.”
It's possible that's true, but it's more likely she's wrong. When you manage a risky project, you need access to more than just technical strengths, you need access to all the other things that make people succeed at work — their personalities. If you hire similar personalities, your staff will have the same blind spots.
If your HR group does personality testing, don't let them pigeon-hole people. In MBTI terms, INTPs make the “best” architects — but not all INTPs want to be architects. SJs aren't the only people who can manage projects, NTs can do so, as well as NFs and SPs. Of course, if you have an NT project manager, ask questions about how that person knows how to acquire the necessary details and finish the project.
It's useful to know about personality types. Rebecca says, “if you find out your coworker … is apparently hardwired to [act in a certain way] you might judge him less harshly.” It's helpful to know personality types, to make sure you have diverse groups and that you're aware of everyone's blind spots. Just don't hire an entire group of one type. You'll miss out on the best diversity of all, that of personality.