The Big Five model was extracted from English language words describing personality (later applied to other languages, where sometimes 6 factors are needed). It has no theory behind it (other than, "I think languages evolve to capture interpersonal dynamics").
As feanaro noted, the 4 dimensions of MBTI is fairly correlated with four of the five factors of the Big 5 (or OCEAN) model. It leaves out neuroticism, which might be helpful in a business context, since you can put a positive spin on both ends of those 4 dimensions. I've seen MBTI extended by adding a Turbulent-Assertive axis to include neuroticism without the pejorative label.
Research has shown that classifying people into the 16 types reduced the statistical predictive power. Nevertheless, the types have value for didactic purposes. It can be easier to understand personality differences by contrasting the extremes rather than the vast muddle of people near the median. Once you can see how extreme differences manifest, it is easier to recognize the more subtle (and statistically more frequent) differences.