I think your view of the MBTI-traits is a little too black and white. Being an introvert indeed does not meen that you lack communicatoin skills or are uncomfortable in social situations, it only means that you enjoy solitude more than an extroverted person, and even need it sometimes because social situations can be draining. It basically could be described by getting your energy from being alone VS getting it from being with people.

The other traits aren't meaningless either, though I think their naming can be a little misleading. For example, always keeping deadlines or finishing prior to them is a high indicator of someone being a J. Ss tend to be more detail oriented, in-the-moment people, why Ns see the big picture, etc. I think if you spend some time really understanding the MBTI it can be of great help in dealing with people that are different than you.

So what I'm really trying to say - those traits don't describe how people behave, but how they process information and handle certain situations.