Avraham didn't feel the need to enforce his will with power, it was okay for him to be a ger. Without kibbush society would not progress. We would have no new science or engineering, no new territory, evil would not be vanquished. But kibbush must have limits. R. Aharon finds in this distinction the source of the gender differences in halachah.
Males have a tendency toward uncontrolled kibbush, while women are more focused on chazakah.
This places women on a higher spiritual plane than men. Will than she is. The reason for the extra mitzvos and extra ritual placed on males is to reign in that uncontrolled kibbush. R. Chaim Soloveitchik holds that there is a distinct difference between the sanctity of Eretz Yisroel that came with the first commonwealth and that of the second. The Second Commonwealth was merely an immigration of a group of Jews who decided to live in the land as Jews.