Hashem does not want Moshe Rabenu to convince the Jewish people to accept. He wants them to accept due to the understanding of the truth and value of the Torah. Hashem does not want the people just to perform good deeds out of custom or ceremony, but to understand the truth of the Torah. Doing the misvot with this understanding will provide the desired effect of perfecting one's nature. The job of any good Rabbi or teacher today is to show the people the truth of the Torah.
People today are extremely sophisticated and wise.
Once the person sees the absolute truth of the Torah, he will automatically pursue it. The Torah sells itself. No convincing is necessary. This could easily have led to much quarreling and arguments. The Kotzker Rebbe replied that since one of the traits required was the attribute of truth, there would be no problem.