Daf Yomi Inisghts - Berachos 28

Rav Yitzchok Meir Morgenstern explains that the disagreement between Rebbe Yehoshua and Rabban Gamliel as to whether Maariv is obligatory or not is connected to how Likutei Moharan explains the distinction between Moshe and Aharon. Moshe represents the higher nekudah, Yehoshua the lower one. Yehoshua represents the more lenient approach the one whose goal is to rectify the lower souls, and for this reason Rebbe Yehoshua, who shares the same name and soul says that Maariv is optional, it is inappropriate to obligate the lower souls to daven when they find themselves in a state of darkness and inability to discern God. We cannot make demands of them, rather we must approach them with love and encouragement, and to offer them the opportunity to pray. Rabban Gamliel who, similar to Moshe, was the leader of the Jewish nation represents the higher point, the people who can handle a stricter approach, he was strict about Maariv being obligatory  and strict about only allowing into the Bais haMedrash people who external behavior reflected what was true about them internally. These were the type of people who could past the strictest tests and could be obligated to daven even during times of darkness, and whom one can inspire and make demands of.
With Rabban Gamliel's removal from his position of leadership and everyone being permitted to enter the study hall, even those of apparently lower stature entered and were able to find the point of goodness and consistency within themselves. This necessitated the appointment of Rebbe Elazar ben Azariah as the new leader because he was the one who had taught that we mention the Exodus from Egypt at night, the ability to inspire those who were lost in darkness and remind them that in Egypt the people were able to be extracted from being mired in the lowest levels of impurity, and in one night they left and beheld the light of the Schechina.
All of this was facilitated by Rebbe Shimon bar Yochai because he understood the true will of Hashem, that He does not wish to conduct the world with the trait of din, strict justice, but, rather, to constantly clearly show the people his deep love.