The Lord asks fair judgment of his efforts. It is clearly a loaded question, because the question is directed specifically at Judah and Jerusalem. They must acknowledge the proper care of the Lord, thus condemning themselves. The care of the Lord is never on question it is we, like Israel who fail in our part of the promise.
The language o the Lord's lament for the failure of the vineyard to match his preparations is virtually identical in Zenos' allegory:
Jacob 5:41: And it came to pass that the Lord of the vineyard wept, and said unto the servant: What could I have done more for my vineyard?
The correspondence of language in these two passages suggests a linkage between them. That linkage at the level of meaning is so understandable in the context of the allegory that one need not suppose any copying in the ancient text. On the level of the English representation of that meaning, however, the general trend of the Book of Mormon to mimic KJV style is sufficient explanation for the similar casting of the similar meanings.
Language note: The sole difference between the KJV text and the 2 Nephi text in these two verses is in the final punctuation of verse 4. In the KJV there is a question mark (noted in the brackets above) and in the 2 Nephi text there is a period. While it makes no real difference in the meaning of the text, the Book of Mormon reading reflects a more modern understanding of English than that of the KJV. In modern English usage, "wherefore" is a causative conjunction. It links two clauses, with the second being the result of the first.
In KJV dialect, however, "wherefore" is a question marker now more typically rendered as "why?," or more colloquially, "how come?" It is this question related usage that is found in the famous Shakespearean lament from Romeo and Juliet, where Juliet exclaims "wherefore art thou Romeo?" In the usage of the times, the phrase is asking why Romeo should have his name (understood also to be his lineage, and refereeing the Montague/Capulet feud).