Ramban explains that the mitzvot are fundamentally tied to Eretz Yisrael — while Jews observe them in the Diaspora, it is only as a 'practice' so we don't forget; the true, spiritually effective fulfillment of the commandments is in the Land of Israel.
"וּמֵאמַר קַדִּישִׁין שְׁאֵלְתָא", כְּלוֹמַר שֶׁשָּׁאֲלוּ מַה הָרָצוֹן הָעֶלְיוֹן עָלָיו, וְאַחֲרֵי כֵן גָּזְרוּ לְהֵעָשׂוֹת כֵּן. וְזֶהוּ שֶׁאָמַר לוֹ דָּנִיֵּאל (שם פסוק כא) "וּגְזֵרַת עִלָּאָה הִיא", כִּי הַכֹּל מֵאִתּוֹ יִתְבָּרַךְ. וְהִנֵּה הַשֵּׁם הַנִּכְבָּד יִתְבָּרַךְ אֱלֹהֵי הָאֱלֹהִים בְּחוּץ לָאָרֶץ, וֵאלֹהֵי אֶרֶץ יִשְׂרָאֵל שֶׁהִיא נַחֲלַת ה', וְזֶהוּ טַעַם "וְזָנָה אַחֲרֵי אֱלֹהֵי נֵכַר הָאָרֶץ" (דברים לא טז) כִּי הָאֱלוֹהוֹת נָכְרִים בְּאֶרֶץ הַשֵּׁם וּבְנַחֲלָתוֹ. וְזֶהוּ שֶׁנֶּאֱמַר (מלכים ב יז כו) "לֹא יָדְעוּ אֶת מִשְׁפַּט אֱלֹהֵי הָאָרֶץ וַיְשַׁלַּח בָּם אֶת הָאֲרָיוֹת וְהִנָּם מְמִיתִים אוֹתָם כַּאֲשֶׁר אֵינָם יֹדְעִים אֶת מִשְׁפַּט אֱלֹהֵי הָאָרֶץ".
But the Land of Israel, which is in the middle of the inhabited earth, is the inheritance of the Eternal designated to His Name. He has placed none of the angels as chief, observer, or ruler over it, since He gave it as a heritage to His people who declare the Unity of His Name, the seed of His beloved ones [i.e., the patriarchs]. It is with reference to this that He said, and ye shall be Mine own treasure from among all peoples; for all the earth is Mine, and it is further written, so shall ye be My people, and I will be your G-d, and you will not be subject to other powers at all.