This chapter is Nephi’s farewell. It is a sad farewell. He says, in verse 3, “I pray continually for them by day, and mine eyes water my pillow by night, because of them.” For all that Nephi has attempted to teach his people, it apparently did not lead to a righteous people. It is against that backdrop that we see verses 1 and 2.
Nephi is obviously writing. While he knows that eventually the Book of Mormon will come forth, and eventually will be for the benefit of the remnant of his people, at this time he is writing to a people he knows and among whom he lives. He cannot write everything he wishes he could, and he knows that he has a more powerful communication by the Spirit when speaking. Therefore, “there are many that harden their hearts against the Holy Spirit, that it hath no place in them; wherefore, they cast many things away which are written and esteem them as things of naught.”
It is not clear how much of 1 and 2 Nephi Nephi’s people had, but whatever they had that was written to provide them the word of God, many hardened their heart against it. Within the first generation, the Nephite people have not been able to fully follow Jehovah’s path. It is no wonder that Nephi wrote so much of what they should do, since they were not doing it.