The title of this paper is a question partly prompted by another, prior and perhaps more familiar one: Why be Humean? Some advance this question rhetorically, taking aim, for instance, at the categorical nature of the Humean base. But I ask it in earnest, and my primary concern is with the structure of the base, the Humean conception of reality as a mosaic of independent elements arrayed in spacetime. I seek to clarify the content and appeal of this metaphor, partly with the aim of understanding the spirit of Humeanism itself, and partly with the aim of framing Humeanism as a case study from which to explore questions, of quite broad philosophical interest, about the relationship between metaphysical and spatiotemporal structure. After revisiting some familiar elements of Humean doctrine, I explore the prospects for combining these with a holographic conception of worldly structure—one that rejects a natural association between metaphysical intrinsicality and spatiotemporal locality, thereby divorcing Humean reductionism from a certain kind of localism. Differing attitudes toward this holographic proposal reflect differing understandings of the association between metaphysical and spatiotemporal structure within the Humean framework.