I totally understand why and how soft skill can be powerful tool at professional workforce. Yet, when I get into very detailed "geeky" kind of work, I often undervalue the soft skill. How do you balance very technical discussion with soft skill?

As long we keep away the soft skills from our personality. There will be always moments when your true personality is coming out. Until they did not become PART of your personality there will be always moment as you mention. It is like two separate objects { You } && { soft skill }. So you have to become one, my friend! ...