Thoughts on introversion, extroversion, and related controversies

Try the quiz linked via the graphic, to answer 20 questions all skewed towards extroverts

Most of my socal media profiles openly declare my self-identification as an INTJ (estimated to comprise 1-2% of the population, and popularly depicted in fiction as antagonists or anti-heroes). I've tested as such since I was 11, though during my university years I came close to registering as INTp. Of course, Myers-Briggs has had numerous valid detractors, and one criticism is that the dichotomies of I-E etc. are not quantified by the labeling: that is, one cannot tell just how strongly introverted I believe myself to be. And since it's a self-identifying classification, one could easily delude oneself into believing that inclination is manifesting directly into actions, meaning that others may not classify one as belonging to that type at all. Nevertheless, lately there have been quite a bit of confrontation between the two camps, where one normalizes one's preference and marginalizes the other. Being in the perceived minority yet again, I can't say that I've been impressed with the arguments presented by either side - but personally, introversion has never been a point of concern, and less so after ex-patriating to outside of North America.
Certainly, it should be no secret to introverts that socialization is encouraged for the most part, and conversely, expressing predilection for spending time by oneself is (at best) treated as a weird quirk, or at worst, a sign of mental disease. Isolation (in the solitary confinement sense in prisons) has also been claimed to be torture. Business situations certainly call for networking, interpersonal and inter-organizational engagement, and it's presumed that extroverts, since they tend to enjoy such opportunities, will generally fare better in them, for several assumed reasons.
However, establishing a reasonably successful career necessitates that an individual explores and confronts their weaknesses, at the same time as playing to her or his strengths. Thus, no matter how disinclined one may be to schmoozing, networking, and elevator-speech delivering, being employed drives one to hone all such skills, and anecdotally, I've found that one's proficiency in gaining such is not correlated necessarily to one's preferences, but rather one's innate capacity combined with effort and making it a high priority to attain.
Before anyone asks, I have not yet read Susan Cain's bestseller, whose title I'll contract to just "Quiet". Part of this being that I haven't access to much English language material locally (I prefer to borrow rather than purchase books, already having a burgeoning collection and a dearth of shelving), but mainly this is due to my already having been sold on the concept of introversion having merit and some advantages.
With that disclaimer, I'd like to present a few observations and opinions of my own, coming from a significantly biased perspective:

• "Thinking aloud", especially in meetings, often comes across to me as wasting everyone's time. Is it not polite to formulate one's position, preferably with substantiable reasons, before opening one's mouth?
• Having been raised at home with the cultural attitude that "Silence is Golden: only break it if you know you can improve upon it", I was penalized for well over a decade in Canadian schools by the extroverted mindset. My teachers frequently, and erroneously, concluded that I was disinterested (not true much of the time), had no opinions (also almost always false; I simply took too long to arrive at my conclusions), and lacked confidence (the most persistent and mistaken of the trio of misunderstandings).
• I believe that generally speaking, it is extremely difficult to get to know others in a group context, particularly since even observing them means the information gleaned only comes from how they happen to behave amongst that particular set of people, and said behaviour can shift dramatically. Small talk may have its place, but it's singularly inefficient as a style of conversation, so I would prefer comfortable silence over stilted, shallow exchanges. I would certainly prefer deeper discussion over either of the former two, with just one or two individuals at a time.
• Extroverts are also capable of (or vulnerable to) clinical depression and demonstrating withdrawn behaviours. Introverts may prefer to have periods of solitude or reduced company at times, but this is not equivalent to exhibiting depression. Non-depressed introverts genuinely enjoy their time interacting with others and can lead balanced lives with quality socialization without severe discomfort. 
• Introversion is also not shyness, necessarily - it may speak to feeling drained after being in the proverbial or literal spotlight, but not to an inability to share ideas or opinions with others, or being a poor public speaker. 
• Like sexual orientation, I believe inclinations such as introversion to be on a spectrum as pictured at the top of this post. Most of the population would fall in the mid (not extreme end) zone.
• This article claims that 75% of those with IQs over 160 are introverted - of course, EQ is a separate (and equally important) metric, but I'd be interested in understanding the extensiveness of the research that drew that conclusion.
• The "Quiet" website implies that "Asian-Americans" are baffled by the extrovert-friendly educational system in the US, but this statement irks me also, as roughly half the Asian-American population consists of those inclined to extroversion, too - it's just that in some contexts such as speaking out of turn or embodying that Proverb (17:28) are culturally embedded, serving to mitigate extroverted behaviour.

I'd like to share one final article link concerning how extroverts seem happier than introverts, before I end this rant-esque post. As one of the top comments states, when the survey questions have to do with social situations, of course extroverts who draw energy and worth from said external experiences would report higher levels of happiness. Another example of a skewed survey, indeed, where the "norm" is defined as extrovert-friendly activities, and the preferences of the introvert are largely ignored.