Most critics of minimalism are critics only because they are confused; they conflate minimalism with emptiness. The two differ, subtly.
Emptiness—of a space, in art, or in words and deeds—is derived from the celebration of negative space. It is an ode to the role of that which isn’t in shaping that which is. In contrast, minimalism, whilst still concerned with the power of negative space, is mostly about priority and the exclusion of that which is not imperative. It is concerned with the mindful evaluation and selection of significance. The calling card of minimalism could easily be the question, “What is the most important thing?” Anything that is not that thing is removed.
This difference between minimalism and emptiness is perhaps best illustrated with an image. Imagine a desk with nothing on its surface. Now imagine a desk with only a pen and a notebook atop of it. The first is an empty desk, the second is a minimal desk. This is the line between empty and minimal. The former is the absence of all things. The latter is the absence of inconsequential things.