In my opinion, fixed methods of communication are very important, especially when you are unfamiliar with a person. The past week or two, we learned a number of distinctions between polite and formal Japanese used for "out group" acquaintances, versus the plain form that can be used for family, friends, and coworkers. When I decided to study Chinese, I never bothered to study the fixed expressions in textbooks. To me, they seemed irrelevant, too formal, and not really necessary. And when I lived in China, most of my friends were my age, so I could talk casually and not have to worry about being too polite. But eventually, I started studying at a university there, and I found that although I could express my opinion, I did not know how to request things from a teacher in a way that was comfortable; in other words, I always had to hesitate, because I was afraid I was being rude.
Now, studying Japanese, which puts so much emphasis on politeness levels, although the variations seem a bit abstract, I realize they'll be very useful when living in Japan or doing research there. To talk to ones friends is easy, because they can overlook small mistakes. But to avoid making an impression that makes strangers reluctant to get to know you is important if you plan on staying in a different culture for a long time; fixed expressions become very important for communication then.
I couldn't write this in Japanese, but I thought the experience in China was worth writing about....gomen nasai!