I can't speak to the two others that you mention, but we use the MBTI because it is well researched, well recognized, easy to do and useful.
You shouldn't really use the MBTI to choose a career direction with no other information. But combined with other testing and your own knowledge about your interests and skills, it can provide a great understanding into why you like some jobs and not others, and what is really important for you in a career. The suggested career lists give you some context and further understanding of potential great career areas, but you don't have to stick to the list...You should use the list to get a feel for the types of careers fit you well. Although, many people do end up happiest in a career typical for their type!
It can also help you figure out how to be happier in the career you are already in!
Learning about personality type can also help with interpersonal relations at work, or outside of it. So it can come in really handy in coaching also.