I think that comment actually misses Susan Cain's point entirely. Here's a quote from Ms. Cain:
"Shyness and introversion are not the same thing. Shy people fear negative judgment, while introverts simply prefer less stimulation; shyness is inherently painful, and introversion is not." [1]
If you accept that definition of shyness, then it is necessarily bad. Living with fear and pain is bad. Missing opportunities to connect with people because of a remote possibility of being hurt is bad. Simply wanting more time to yourself is not.
Regarding fault, it doesn't really matter who's to blame (and I didn't see anything in the article about fault). As an example, some people are born with type 1 diabetes and have to constantly manage their blood sugar levels. It's not their fault that they were born with this disease, but it's their problem to manage it. The same goes for shyness. Your shyness may not be your fault, but you're the only one that's hurt by it.
"Shyness and introversion are not the same thing. Shy people fear negative judgment, while introverts simply prefer less stimulation; shyness is inherently painful, and introversion is not." [1]
If you accept that definition of shyness, then it is necessarily bad. Living with fear and pain is bad. Missing opportunities to connect with people because of a remote possibility of being hurt is bad. Simply wanting more time to yourself is not.
Regarding fault, it doesn't really matter who's to blame (and I didn't see anything in the article about fault). As an example, some people are born with type 1 diabetes and have to constantly manage their blood sugar levels. It's not their fault that they were born with this disease, but it's their problem to manage it. The same goes for shyness. Your shyness may not be your fault, but you're the only one that's hurt by it.
[1] http://ideas.time.com/2012/01/26/dont-call-introverted-child...