There are hard sciences, soft sciences and pseudosciences, and unlike, say, astrology, temperament psychology — in any of its better-established varieties, including the Myers-Briggs typology and the Big Five — belongs (along with most of psychology) in the "soft science" category.MBTI is a pseudoscience but it doesn't mean it should be treated like a buzzfeed quiz.
Carl Jung — mystical streak notwithstanding — was a believer in the scientific approach, and Isabel Myers took Psychological Types and devoted a substantial chunk of her life to putting its typological concepts to the test in a way that Jung never had, and in accordance with the psychometric standards applicable to the science of personality. Myers adjusted Jung's categories and concepts so that they better fit the data she gathered from thousands of subjects, and by the start of the 1960s (as the leading Big Five psychologists have acknowledged), she had a typology that was respectably tapping into four of the Big Five personality dimensions — long before there really was a Big Five. And twin studies have since shown that identical twins raised in separate households are substantially more likely to match on those dimensions than genetically unrelated pairs, which is further (strong) confirmation that the MBTI dichotomies correspond to real, relatively hard-wired underlying dimensions of personality. They're a long way from being simply theoretical — or pseudoscientific — categories with no respectable evidence behind them.
You talk about Myers "bastardizing" Jung because she wanted "easy recognition," and you really couldn't be farther from the facts, and you should be ashamed of yourself. If it wasn't for Myers, chances are pretty good that few of us would ever have even heard of Psychological Types, which was largely ignored until Myers did the necessary data-gathering to figure out how the personality characteristics that Jung had focused on actually clustered in real people.
Jung included what's arguably the lion's share of the modern conception of S/N (the concrete/abstract duality) in his very broad notion of what E/I involved. But Myers discovered that there are abstract extraverts (ENs) and concrete introverts (ISs), and that there's no significant correlation between Myers' (statistically supportable) versions of E/I and S/N. Jung said extraverts tend to subscribe to the mainstream cultural views of their time, while introverts tend to reject mainstream values in favor of their own individualistic choices. But Myers discovered that a typical ISTJ is significantly more likely to be a traditionalist than a typical (more independent-minded) ENTP. Jung said an extravert likes change and "discovers himself in the fluctuating and changeable," while an introvert resists change and identifies with the "changeless and eternal." But Myers discovered that it was the S/N and J/P dimensions that primarily influenced someone's attitude toward change, rather than whether they were introverted or extraverted.
And so on. The appropriate way to view the Myers-Briggs typology is not as some kind of "bastardized" — or simplified (or more "testable") — version of Jung's original typology. Instead, it's fairer to say that the Myers-Briggs typology is basically where Jung's typology ended up after it was very substantially modified — not to mention expanded — to fit the evidence.
Anyone who's interested can read quite a lot about the scientific respectability of the MBTI — and about several other issues often raised by people claiming to "debunk" the MBTI — in this post and in this post (also linked to in the first linked post).
Buuut contrary to what your fact-challenged posts might lead someone to believe, the scientifically respectable side of the MBTI is the dichotomy-centric side — and the dichotomies differ greatly from the so-called "cognitive functions" in that regard. The functions — which James Reynierse (in that 2009 article I've already linked you to) rightly (IMHO) characterizes as a "category mistake" — have barely even been studied, and the reason they've barely been studied is that, unlike the dichotomies, they've never been taken seriously by any significant number of academic psychologists. Going all the way back to 1985, the MBTI Manual described or referred to somewhere in the neighborhood of 1,500 MBTI studies and, as I understand it, not one of the many study-based correlations reported in the manual were framed in terms of the functions. The third edition of the MBTI Manual was published in 1998 and, as Reynierse notes in that same article, it cited a grand total of eight studies involving "type dynamics" (i.e., the functions model) — which Reynierse summarizes as "six studies that failed, one with a questionable interpretation, and one where contradictory evidence was offered as support." He then notes: "Type theory's claim that type dynamics is superior to the static model and the straightforward contribution of the individual preferences rests on this ephemeral empirical foundation."
And contrary to the notion that a function-centric perspective offers more richness and depth than a (properly framed) dichotomy-centric perspective, and as Reynierse rightly points out, it's actually the dichotomy-centric perspective that's richer and more flexible.
Myers spent quite a lot of Gifts Differing talking about aspects of personality that corresponded to any number of dichotomy combinations, including the combinations that purportedly correspond to the cognitive functions. But it's worth noting that she really didn't treat the function-related combinations as if they had any special significance — and in fact, Myers thought the most meaningful preference combinations were ST, SF, NT and NF (each of which includes four types with four different dominant functions).
In any case, though, any deep, true thing that can be said about a (supposed) Ti-dom, for example, can just as well be said about an I_TP. If you're looking for a limiting framework, give a listen to any of the large number of forumites whose posts indicate that the MBTI "letters" really don't say much about anyone, and that INTJs and INTPs have little in common — because I and N and T (and the IN and NT and IT combinations) pretty much just correspond to trivial "surface" stuff. There's the limiting and impoverished perspective if you ask me. And it certainly isn't a Jungian perspective. Jung spent more of Psychological Types talking about the things he thought extraverts had in common and introverts had in common than he spent talking about all eight of the functions put together.