וְעַתָּ֣ה ׀ אַל־תֵּעָ֣צְב֗וּ וְאַל־יִ֙חַר֙ בְּעֵ֣ינֵיכֶ֔ם כִּֽי־מְכַרְתֶּ֥ם אֹתִ֖י הֵ֑נָּה כִּ֣י לְמִֽחְיָ֔ה שְׁלָחַ֥נִי אֱלֹהִ֖ים לִפְנֵיכֶֽם׃
Agora, portanto, não vos entristeçais, nem fiqueis irados convosco mesmos por me haverdes vendido para cá, porque foi para preservar a vida que Elohim me enviou adiante de vós.
Akeidat Yitzchak
Expulsion was necessary to maintain the nature of man. Had man's lifespan become unconditionally infinite through his eating from the tree of life, he would no longer have been a unique creature in the universe. He would have become a sub species of the celestial beings. By having to maintain a balance between the animalistic and the Divine, and by constantly having to face this challenge, he could remain human. Therefore, the gates of Eden had to remain closed to him.