Every week I go to a free Korean class. There are actually two I know of in my vicinity, but they overlap. Anyhow, the second level (the first basically teaches students how to read hangul characters) started again today. This meant a new teacher.
The new teacher emphasized grammar. In order to mark the location of the subject of a sentence, there is a grammar particle after it. The grammar particle differs if it comes after a vowel or consonant. It differs if the subject is considered a topic, and not simply the subject of that sentence. Alone, you might choose the topic marker or the subject marker depending on how you want to emphasize the subject of the sentence. For example, showing the subject of the sentence is different. "The baby is crying." would be different grammatically than "The baby is crying, though other people are too."
Most people in class were confused, because there wasn’t a simple rule about when to use which type of marker. People looked at me, and said I can use them pretty well. I pointed out I didn’t pay much attention to grammar at all – I just try to emulate what I hear from native speakers.
I still continue to think vocabulary in context is the basis of a language, not the grammar. Listening ability comes next. Grammar is only important when you get to a point that people understand all the words you use, think you are speaking clearly, but do not get the logic in the way you have constructed a sentence. Nobody in my class has progressed that far in grammar.