It's her progression as an artist. With ARTPOP she wanted something that makes her happy when she's on stage to sing every night. From what I understand it was a very emotional time in her life and the album reflected that. It was probably hard to sing certain songs like You and I because it reminds her of the past. I love Born This Way as well, and I know Gaga will always treasure it like us. You can just tell that during the artRAVE she seems to be so happy to be singing the setlist. It's beautiful <3

thanks for the replies

that's because BTW was a dark album and Gaga went through dark times..but now she's really happy and wanted to bring a light and color to ARTPOP :) I think that's okay :)

Born this way just was a test to knew who were her really fans