Why preserve an artist's palette?

A brilliant writeup in the London Telegraph by Sunday Seven Magazine Picture Editor Lucy Davies about the preservation of artists' palettes in order to gain insight into their process and methodology:

"Why preserve an artist’s palette? The daubs of raw pigment or the mixes left in position can be an intriguing index to the working method and the mind of the artist. And most, once the status of art had been elevated above the realms of mere craft, would paint themselves palette in hand..."

Eugene Delacroix