For me, it helped me to open my mind more in understanding how I and other people think and act.
A friend of mine wondered why she disliked being an accountant. She was very good at her job, but there was just something nagging her that she didn't like. Then she learned about MBTI and found out that her type was ENFP. It helped her to realized that she really did not like being isolated all day doing detail-oriented work. She went back to school to working towards a degree in Elementary Education.