The reconstruction period had generally good ideas which were exploited by bad people and who turned it all upside down. The idea of reconstruction was to integrate African-Americans into the society and protect their rights and enable them to educate themselves and become sophisticated and emancipated members of the society.
During the gilded age, the focus switched form social to economic reforms and because of this the reconstruction ended and many southern states reverted to their original racist ways. This is why it's called the gilded age, it only looked like everything was great but it was bad at its core, like gilded items which only look gold.