Before leaving Egypt, Moshe was instructed by G-d to tell the Children of Israel to request silver and gold vessels from the Egyptians (Ex. 11:2). Miraculously, the Egyptians agreed to this. The Jews took these riches with them when they eventually departed.
This was not a new idea, since more than 400 years earlier G-d had promised Avraham this in the “Covenant of Parts” (brit ben habetarim). Avraham’s offspring would be enslaved for hundreds of years by another nation, and when the servitude would be over, Avraham’s offspring would leave with “great wealth” (Gen. 15:14).
In fact the Talmud (Ber. 9a) adds that when Moshe was asked by G-d to tell the nation to request riches from the Egyptians, he did so in a manner of “pleading”, lest Avraham (in the Heavenly realm) say to G-d that “You fulfilled Your promise of enslaving them, but You did not fulfill Your promise that they would leave with riches and wealth”. Why was this material acquisition such an important element of the Exodus that it was guaranteed from the original prophecy and so insisted upon at the end?
There was a possibility that leaving Egypt would be taken by the people to be a new start, a new dawn, a wiping clean of the old slate. The countless years of servitude were painful and perhaps best forgotten. Now they could forward to a better, brighter future. Look ahead, no need to look back.
However, to have adopted such an attitude would have been a travesty, for invaluable lessons were learned from the experience in Egypt. The nation saw that however bad circumstances could get, the nation would still survive. They clung onto a promise of redemption, which was ultimately fulfilled with an entrenched national emuna (faith) in G-d. They saw that the Egyptians were eventually punished with the miraculous Ten Plagues, which showed G-d’s mastery over the world. They learned the benefit of hanging onto key facets of their Jewish identity, which the Midrash relates was the merit in which they were redeemed.
In fact, the Maharal of Prague (Rabbi Yehuda Loew) writes that the Egyptian experience was far from a dispensable obstruction. On the contrary, it was the necessary backdrop for the birth of the nation.
Hundreds of years earlier, Avraham was concerned that the “Egyptian experience” would be only negative for his descendants. A forecast of slavery and suffering with no clear purpose would have been without meaning. He hoped that the bitter experiences would ultimately be productive.
G-d was actually promising Avraham that the Jews would leave Egypt with a national experience that they could build on for the rest of time, a promise that He eventually carried out. That was a great spiritual inheritance. The physical wealth was not an end in itself. It was actually a physical reminder of the fact that they were not leaving either physically or spiritually empty-handed. It had not been a pointless experience. It was in fact the unforgettable circumstances in which a nation was born.