The Pe'as Hashulchan, Laws of Eretz Yisroel, Chapter 1, Section 3, quotes the words of the Rashbash, who says that settling in Eretz Yisroel is not a mitzvah on all Jews nowadays, only on individuals. Therefore, if it is easy, one should go, but if there are considerations that prevent him, he should not go. The Pe'as Hashulchan explains that the Rashbash was bothered by the question of how the existence of such a mitzvah even today is consistent with the Three Oaths. The Rashbash's answer is that if the mitzvah were incumbent upon every Jew, the entire Jewish people would be obligated to go to Eretz Yisroel, and they would then violate the Oaths. But actually the mitzvah is only on individuals, and is not obligatory; therefore other considerations take precedence over the mitzvah.
For example, if one's wife does not wish to come with him he should not divorce her and go, for perhaps he will not find another wife there, or perhaps he will find one but it will cost too much. The Sages even say that one may leave Eretz Yisroel to get married (Rambam Melachim 5:9) – certainly then one should not lose his wife by going there. Similarly if he has children and cannot leave them he should not go.