Because not everyone is willing to go along with the pursuit of ever-more-and-more-exacting degrees of accuracy no matter what it costs. MBTI is good enough for the purpose.

Except that it isn't. That's the take-home point I'm trying to make. It's not good enough--it's not good at all. It doesn't accurately tell you anything about the inquirer's personality. It spits out a type that may or may not describe you. MBTI is absolutely not good enough for the purpose, and there are mounds of studies confirming that it is not good enough.

Big 5 is good enough for the purpose.

Did you read my post? Big Five = NEO-PI-R, effectively. They test the same dimensions. That being said, businesses should be willing to pay for quality, official personally testing of they care enough about testing in the first place. You invest in quality results. That's one if the prime rules of running a good business.

Further, you seem to be under the impression that the only purpose for testing personality is corporate in nature. This is not the case.