2. Communication is the ultimate goal
Why do we learn grammar of a language? Why to we repeat vocabulary? Why do we write texts, why do we translate and practice? Because we want to be able to use the language to communicate with other people. Therefore, communication is the ultimate goal.
For being able to handle a language in a communicative matter, we have to know the structures and grammatical rules. We have to learn words in form of adjectives, nouns, adverbs, articles, prepositions and conjunctions. The structure of the language has to be understood. But these are only small milestones on the way to the ultimate goal, the goal of being able to communicate. That is why it's important to know, that we learn a language to speak it. Some people might think this is clear, but many of my students were afraid to speak. They wanted to understand and practice, but speaking with mistakes can be uncomfortable for some. But mistakes are great! They show you what you've already learned and tell me, what is clear and what we have to work on still. So: Speak, speak, speak!