There is some debate in the Talmud as to whether בני ישראל were interested in receiving gifts of gold and silver from the Egyptians. Although these reparations were certainly deserved, many did not care for two reasons.
One was that the only thing that interested them was their freedom after such a long and difficult slavery. Material objects were not nearly as important as freedom.
The other reason for not wanting these gifts is that they would weigh them down. They wanted to get out of Egypt quickly and being loaded down with all of these objects was likely to slow them down.
Nevertheless, Hashem reiterated the importance of keeping His promise to the Tzaddik, Avraham Avinu. He said that it would be difficult to face Avraham after fulfilling the ועבדים ועינו אותם, the enslaving and torturing, and not fulfill the רכוש גדול, the great wealth part of the promise. Hashem always keeps His word.