It is true that God caused us to descend to Egypt because of our transgressions, but this explanation is certainly insufficient. The sojourn in Egypt, the struggle to be free, and the redemption from there are recalled as essential experiences which shaped and formed the Jewish nation. The Jewish people become a unified whole as a result of having passed through the proverbial crucible of suffering. For this very reason, our sages explained in various midrashim the additional dimension which accrued to the Jewish people as a result of the exodus. The Maharal discusses this same dimension, namely the spiritual enrichment of the Jewish nation, with respect to the salvation brought about by the Maccabees.
Every person contains hidden strengths and weaknesses.
All of us pass years of our lives in routine and habit, which are punctuated by periods of challenge. During such testing times, many of one's latent abilities are revealed. When a person faces the danger of death, for instance, hidden reserves of strength come to the fore. Insights and leadership talents are suddenly revealed which are not at all expressed during normal life. There are those who find God precisely at times of struggle, and during trials of faith.