Knowing personalities is certainly essential. But, I think if you want to find that out, it's better to interact with them and form your own opinions and talk to others who've done the same. Using a 4-dimension set of binary states (just to pick on MBTI here) will only tell you what you could have found out faster, cheaper (there's an industry around these things), and without making the person feel like a replaceable part.
In an interview situation (where you have less time to decide than building an internal team), that could mean going through hypothetical situations and finding out how they would solve a problem, having multiple interviewers, and checking on references. Having them take a personality test beforehand sends a signal that as an employer, you're not willing to take the time to get to know them, which starts everyone off on the wrong foot. Also, IANAL, but it sounds like a lawsuit waiting to happen.
In an interview situation (where you have less time to decide than building an internal team), that could mean going through hypothetical situations and finding out how they would solve a problem, having multiple interviewers, and checking on references. Having them take a personality test beforehand sends a signal that as an employer, you're not willing to take the time to get to know them, which starts everyone off on the wrong foot. Also, IANAL, but it sounds like a lawsuit waiting to happen.