This is my general take, too.

Taking just extroversion for example, I know people (we all do) whose emotional stability seems to require almost constant networking and meeting new people. I've tried to fake this ability, and learn it...because it is a great way (sometimes the only way) to be successful in certain areas of business. Most people would never guess it (so I guess I'm doing a decent job of trying to be extroverted), but I'm strongly introverted, and it takes great effort for me to become the Networking Version of myself for a couple hours at a business event or happy hour.

Over time, I believe this effort to be extroverted takes a significant toll on my overall mood and motivation levels. In order to be something you aren't, you are basically engaging in something you are really bad at and don't enjoy -- which tends to wear on my self-image. And in the case of extroversion, you are meeting contacts and forming friendships under some false-ish pretenses, since you are only pretending to be that way. In some cases, people will expect you to be the Extroverted Version indefinitely, even though you were just wearing that hat and trying to adopt those habits in the way the post suggests.

Though you can (and I have) become a pretty passable faux-extrovert, I think it can be (and has been for me) a net bad choice. I shoulda just been introverted, neurotic and depressive all along, and focused on the comparitive advantages those traits have to offer.