I agree that we shouldn't focus too closely on individuals and their personality types. There is some discussion about whether this changes over time. You don't want to box people in too much.
What I came away with after examining this idea, was that we aren't meant to go it alone in terms of decision making. Our personality types blend together to provide a kind of over-mind that is greater than its individual parts.
I agree that it's most important for individuals to discover their own personality type, especially as it serves as a rite of passage into understanding and reconstructing interpretations of oneself and others in terms of MBTI.
I don't think MBTI would be as bad as other forms of bigotry at all however. I believe that essentializing difference is an unavoidable human trait as the mechanism that causes it is necessary for our survival (otherwise everything would constantly overwhelm us as new), but there are limits to how sereve it can be with MBTI. MBTI is fundamentally recognized as variant, which I think could easily be ignored, but much less so than with other forms of identity.
Unlike other forms of identity, seminal texts about MBTI are not spatially or temporally dependent, allowing them to have a greater depth of analysis without requiring high amounts of contextualization. Race, sexuality, gender, class, ect. are all so transient through time and space, but personality inclinations are more innate than these more superficial constructs of self.
Social identity and prejudices tend to develop unconsciously, especially if it develops in a society in which it is dominant and therefore can go permanently unexamined. For example it's much more difficult for many homosexuals to develop prejudice against heterosexuals that doesn't correspond with lived experience when the majority of people are heterosexual, so understanding heterosexuality is compulsory, at least for survival. In contrast, MBTI requires a conscious learning and understanding of both one's own and others' types, making everything equally conscious.
Of course, users of MBTI could still essentialize and generalize to a point of counterproductivity, but I can't imagine it would be worse than how gender, sex, sexuality, race, class, ethnicity and culture are generalized. in other words, MBTI is the lesser of all evils as an identity model.
I think MBTI can also promote what Craig has said, that all personality types are necessary for the suprastructure of humanity.