Nephi calls his brothers on their mistaken assumption. It is not the Lord who declines to communicate, but the hardness of our hearts which causes us to decline to ask. Nephi does understand that it takes more than the simple question, however. Our right to obtain answers from God is tied not simply to the asking, but to the righteousness of our hearts with which we ask. In Nephi's case, his life to the point of his asking demonstrated his faith and willingness to serve the Lord. Laman and Lemuel's did not. It is no wonder that the revealed no such things to them.
It is also important to note that Nephi's explanation of how the answers are received include aspects of faith and diligence which long preceded the question. When Nephi asked, he asked. He did not go to the desert to prepare for several days before asking. He asked. Nephi's faith and diligence was sufficient preparation that when he needed to ask he was worthy of the answer.