Why should this news particularly please Pharaoh and his servants? Rabbi Joseph B. Soloveitchik explains that having an ex-con like Joseph in such a position of authority did not sit well with the Egyptians. Now it was made known that Joseph was descended from the famous Abraham, which was tantamount to noble lineage. Additionally, given all that Joseph had done for Egypt, Pharaoh eagerly anticipated all the contributions that an entire family of such individuals might make. (Cited in the Mesoras HaRav Chumash.)