[76b top] Gemarah: It is forbidden for one to leave Eretz Yisrael.
Rashi: This is referring to one who lives there.
RambaN: There is a specific special Biblical Mitzvah for us all to live in Israel.
RambaM (according to most opinions): There is, even nowadays, a Mitzvah for us all to live in Israel, but it is included under the larger category of other listed Mitzvos [ie: kicking other nations out of our land].
Megillas Esther: The RambaM does not record this in his complete list of Mitzvos because it does not apply when we are exiled from our land.
R’ Rosner: In so many other Mitzvos, we look for the most choicest ways to fulfill them (even way beyond the ‘letter of the law’), but by this law people are willing to rely on one minority lenient opinion to get out of having to live in our Holy land.
D-E-ep Thoughts (based on R’ Rosner): We always have to be honest with ourselves, and act for Hashem with pure intentions. We must never let physical comforts cloud our judgement. When we recognize real obligations, we should not look to rely on loopholes (no matter how legitimate). We should strive not just to be “Tzaddikim” (completely righteous), but to become “Chassidim” (acting from love with overflowing devotion).