There is perhaps nothing more integral and essential to a Guardian than their Ghost. In Destiny 2, the Ghost is what gives Guardians their Light, their immortality, and strength. Due to the bond between Guardians and Ghosts in Destiny 2, its safe to say that they would want their little light to have a way of expressing themselves, which is exactly why they can find some of the best Ghost Shells in Destiny 2 to live in like a nice new coat.