"And Jacob lived in the land of Egypt seventeen years, and the years of his life were one hundred and forty seven years" (Breisheet 47:28).
One of the Rambam's principles of faith is the eternity of the Torah. While historical circumstances may prevent the performance of certain mitzvoth, the mitzvah of Talmud Torah encompasses these "theoretical" mitzvoth as we hope that these mitzvoth will soon move from the theoretical realm to the practical.
After close to 2,000 years in exile, mitzvoth that were once dormant have come back to life. The Torah is no longer just a guide for individual living--it is the template for a nation back in its homeland.
Life is so unfair. While we believe that ultimately (and ultimately can take an eternity!) justice must and will prevail—to believe otherwise would be to deny the essence of Judaism—it is clear that life is full of injustices. Moshe Rabbeinu was the greatest person who ever lived. Yet he was denied his one wish, to be able to walk in and breathe the air of the land of Israel. Moshe continued pleading his case until G-d "angrily" told him, enough already! Your request is denied.