I'm not dismissing it. It's a valid point; it's just that it only takes one side of the coin into account. There are times when introversion's depth is clearly preferable, and other times when extroversion's breadth is.
And uh, coming from an introverted person implies that an idea is influenced most heavily by an introverted perspective (in most cases), as the introvert's dominant perspective is, by definition, an introverted one.
The same applies to extroverts; we have a natural tendency (at least in regards to our dominant process) to choose breadth over depth, and we have to work on the auxiliary to balance that out.
I am referring to those criticisms as "introverted" because I feel that they fail to take into account the value of extroversion/breadth and thus continually insist that no precision can or should ever be sacrificed for the sake of broader applicability.
The Ti+Ni ISTP from Per-C that I mentioned is largely against inductive reasoning. You can think of introversion as deductive (because it is precise, complete, and certain) and extroversion as inductive (because it sacrifices precision/completeness in favor of wider applicability.) I wrote a post about inferring the types of others based on their behaviors; he found this completely unacceptable as it required use of inductive reasoning.
He said something to the effect of, "Guessing is not certainty." That's certainly a valid point--the problem is, it's a purely introverted perspective that doesn't take into account the relative value of breadth. The idea is to get to a point where we recognize that breadth and depth are equally important, and that which is preferable is context-dependent.